485BPOS

As filed with the Securities and Exchange Commission on February 9, 2015

Securities Act File No. 33-20827

Investment Company Act File No. 811-5518

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	o
Post-Effective Amendment No. 179	x
and
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 181	x

THE RBB FUND, INC.

(Exact Name of Registrant as Specified in Charter)

Bellevue Park Corporate Center

103 Bellevue Parkway

Wilmington, DE 19809

(Address of Principal Executive Offices)

Registrant’s Telephone Number: (302) 791-1851

Copies to:

SALVATORE FAIA BNY Mellon Investment Servicing (US) Inc. 103 Bellevue Parkway Wilmington, DE 19809 (Name and Address of Agent for Service) MICHAEL P. MALLOY, ESQUIRE Drinker Biddle & Reath LLP One Logan Square, Ste. 2000 Philadelphia, PA 19103-6996

It is proposed that this filing will become effective (check appropriate box)

x immediately upon filing pursuant to paragraph (b)

o on [date] pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(1)

o on [date] pursuant to paragraph (a)(1)

o 75 days after filing pursuant to paragraph (a)(2)

o on [date] pursuant to paragraph (a)(2) of Rule 485

If appropriate, check the following box:

o This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

Title of Securities Being Registered                   Shares of Common Stock

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “1933 Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement under Rule 485 (b) under the 1933 Act and that it has duly caused this Post-Effective Amendment No. 179 to its  Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Wilmington, and State of Delaware on the 9th day of February, 2015.

THE RBB FUND, INC.
By:	/s/Salvatore Faia
Salvatore Faia
President

Pursuant to the requirements of the 1933 Act, this Post-Effective Amendment to Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

SIGNATURE		TITLE	DATE
/s/Salvatore Faia		President (Principal Executive Officer) and Chief Compliance Officer	February 9, 2015
Salvatore Faia
/s/Joel L. Weiss		Treasurer (Chief Financial Officer)	February 9, 2015
Joel L. Weiss
*J. Richard Carnall		Director	February 9, 2015
J. Richard Carnall
*Julian A. Brodsky		Director	February 9, 2015
Julian A. Brodsky
*Arnold M. Reichman		Director	February 9, 2015
Arnold M. Reichman
*Robert Sablowsky		Director	February 9, 2015
Robert Sablowsky
*Robert Straniere		Director	February 9, 2015
Robert Straniere
*Nicholas A. Giordano		Director	February 9, 2015
Nicholas A. Giordano
*Gregory P. Chandler		Director	February 9, 2015
Gregory P. Chandler
*Jay F. Nusblatt		Director	February 9, 2015
Jay F. Nusblatt
*By:	/s/Salvatore Faia		February 9, 2015
Salvatore Faia
Attorney-in-Fact

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Julian A. Brodsky, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 7, 2009
	/s/ Julian A. Brodsky
	Julian A. Brodsky

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, J. Richard Carnall, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 7, 2009
	/s/ J. Richard Carnall
	J. Richard Carnall

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Nicholas A. Giordano, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 7, 2009
	/s/ Nicholas A. Giordano
	Nicholas A. Giordano

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Arnold M. Reichman, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 7, 2009
	/s/ Arnold M. Reichman
	Arnold M. Reichman

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert Sablowsky, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 7, 2009
	/s/ Robert Sablowsky
	Robert Sablowsky

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert Straniere, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	May 7, 2009
	/s/ Robert Straniere
	Robert Straniere

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Gregory P. Chandler, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	October 15, 2012
	/s/ Gregory P. Chandler
	Gregory P. Chandler

THE RBB FUND, INC.

(the “Company”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Jay F. Nusblatt, hereby constitutes and appoints Salvatore Faia, Michael P. Malloy, James G. Shaw and Joel L. Weiss, his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director or officer, or both, of the Company, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

DATED:	October 16, 2012
	/s/ Jay F. Nusblatt
	Jay F. Nusblatt

EXHIBIT INDEX

Exhibit No.	Description
101.INS	XBRL Instance Document
101.CAL	XBRL Taxonomy Extension Calculation Linkbase
101.SCH	XBRL Taxonomy Extension Schema Document
101. DEF	XBRL Taxonomy Extension Definition Linkbase
101. LAB	XBRL Taxonomy Extension Label Linkbase
101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Long/Short Research Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term total return.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

1.25%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Dividend expense on short sales

rr_Component1OtherExpensesOverAssets

0.84%

^[1]

Interest expense on borrowings

rr_Component2OtherExpensesOverAssets

0.30%

Other operating expenses

rr_Component3OtherExpensesOverAssets

0.13%

Other expenses

rr_OtherExpensesOverAssets

1.27%

Total annual Fund operating expenses

rr_ExpensesOverAssets

2.77%

^[2]

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 57% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

57.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 280

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

859

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,464

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 3,099

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or "micro")-cap companies, as well as other instruments that are convertible into equity securities. Selling securities short is a form of leverage. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts ("REITs"), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Fund may also invest in depository receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as "junk bonds"). Fixed income securities in which the Fund will invest include those rated between AAA and D by a nationally recognized statistical rating organization ("NRSRO"), or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund's portfolio or investments will be insulated from market moves or effectively hedged against risk.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest up to 30% in exchange-traded funds to the extent permitted by the Investment Company Act of 1940 ("1940 Act") and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund's investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the performance of the Boston Partners Long/Short Research Fund's Investor Class. The bar chart below provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2011

rr_AnnualReturn2011

3.12%

Annual Return 2012

rr_AnnualReturn2012

13.13%

Annual Return 2013

rr_AnnualReturn2013

17.45%

Annual Return 2014

rr_AnnualReturn2014

6.86%

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	8.29% (quarter ended December 31, 2011)
Worst Quarter:	(9.91)% (quarter ended September 30, 2011)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.29%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.91%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

6.86%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

10.52%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

6.52%

^[3]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

10.23%

^[3]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.16%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.21%

S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

13.69%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

16.83%

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total Annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.75% of the average daily net assets attributable to the Fund's Investor Class shares. Because acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total Annual Fund Operating Expenses (after fee waivers and expense reimbursements) are expected to exceed 1.75%.This contractual limitation is in effect until at least January 26, 2016 and may not be terminated without Board approval. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 1.75%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Investor Class Prospectus | Boston Partners Global Equity Fund

Boston Partners Global Equity Fund

Investment Objective

The Fund seeks to provide long-term capital growth.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Investor Class Prospectus Boston Partners Global Equity Fund Investor Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Investor Class Prospectus Boston Partners Global Equity Fund Investor Class
Management fees		0.90%
Distribution and servicing (12b-1) fees		0.25%
Other expenses		0.49%
Total annual Fund operating expenses		1.64%
Less Fee waivers and expense reimbursements	[1]	(0.44%)
Net expenses		1.20%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Investor Class Prospectus Boston Partners Global Equity Fund Investor Class	122	474	850	1,907

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund's Institutional Class was 136% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")) and real estate investment trusts ("REITs"), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer's inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO").An IPO is a company's first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. Redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Performance Information

As of the date of this Prospectus, the Boston Partners Global Equity Fund's Investor Class has not yet commenced operations. The bar chart and table below illustrate the performance of the Fund's Institutional Class, which is offered in a separate Prospectus. Had the Investor Class been operational during the periods in the chart and table below, it would have had substantially similar annual returns as the Institutional Class because the Investor Class is invested in the same portfolio of securities. Annual returns would differ only to the extent that the Investor Class and Institutional Class do not have the same expenses. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risk of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	11.70% (quarter ended March 31, 2012)
Worst Quarter:	(5.91)% (quarter ended June 30, 2012)

Average Annual Total Returns

Average Annual Total Returns for the Period Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Investor Class Prospectus Boston Partners Global Equity Fund		Average Annual Returns, 1 Year	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Institutional Class		4.34%	16.86%	Dec. 30, 2011
After Taxes on Distributions Institutional Class	[1]	2.69%	15.61%
After Taxes on Distributions and Sale of Fund Shares Institutional Class		2.75%	12.78%
MSCI World Index (reflects no deduction for fees, expenses or taxes)		5.50%	16.29%	Dec. 30, 2011

[1] The Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.20% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.20%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 1.20%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year and since inception periods compare with those of a broad measure of market performance.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Small Cap Value Fund II

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

1.00%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.48%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[1]

Net expenses

rr_NetExpensesOverAssets

1.35%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-12-31

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 16% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

16.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 137

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

428

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

769

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,733

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2014, the median market capitalization of this index was $601 million and the largest stock was $4.6 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 175%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II's Investor Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2005

rr_AnnualReturn2005

7.54%

Annual Return 2006

rr_AnnualReturn2006

15.66%

Annual Return 2007

rr_AnnualReturn2007

(7.56%)

Annual Return 2008

rr_AnnualReturn2008

(34.82%)

Annual Return 2009

rr_AnnualReturn2009

48.99%

Annual Return 2010

rr_AnnualReturn2010

18.24%

Annual Return 2011

rr_AnnualReturn2011

(3.67%)

Annual Return 2012

rr_AnnualReturn2012

22.54%

Annual Return 2013

rr_AnnualReturn2013

34.40%

Annual Return 2014

rr_AnnualReturn2014

3.90%

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	29.32% (quarter ended June 30, 2009)
Worst Quarter:	(26.42)% (quarter ended December 31, 2008)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

29.32%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(26.42%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Caption

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Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

3.90%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

14.28%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

8.09%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

3.36%

^[2]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

14.09%

^[2]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.70%

^[2]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.47%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

11.44%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.37%

Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.22%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

14.26%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.89%

[1] The Fund's investment adviser, Robeco Investment Management, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.35% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.35%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time during the three years from May 28, 2014 to May 28, 2017 the Fund's Advisory Agreement with the Adviser is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.35%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund during such three-year period.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Investor Class Prospectus | Boston Partners Global Long/Short Fund

Boston Partners Global Long/Short Fund

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Investor Class Prospectus Boston Partners Global Long/Short Fund Investor Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Investor Class Prospectus Boston Partners Global Long/Short Fund Investor Class
Management fees		1.50%
Distribution and servicing (12b-1) fees		0.25%
Dividend expense on short sales	[1]	1.06%
Interest expense on borrowings		0.85%
Other operating expenses		1.48%
Total other expenses		3.39%
Total annual Fund operating expenses		5.14%
Less Fee waivers and expense reimbursements	[2]	(1.01%)
Net expenses		4.13%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs of investing $10,000 in the Fund would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Investor Class Prospectus Boston Partners Global Long/Short Fund Investor Class	414	1,450	2,483	5,052

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 72% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size.

With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by Standard & Poor's Rating Group, or have a comparable rating by another nationally recognized statistical rating organization ("NRSRO") (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. The Fund will indirectly bear its proportionate share of any expenses, including management fees, paid by an externally managed REIT in which it invests.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Performance Information

The Investor Class commenced operations on April 11, 2014, therefore annual returns for one full calendar year are not available for Investor Class shares of the Fund. The bar chart and table below illustrate the performance of the Boston Partners Global Long/Short Fund's Institutional Class, another class of shares of the Fund that is offered in a separate prospectus. The bar chart below shows you how Institutional Class shares of the Fund have performed on a calendar year basis and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Year Ended December 31 (Institutional Class)*

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	0.89% (quarter ended September 30, 2014)
Worst Quarter:	(0.20)% (quarter ended December 31, 2014)

Average Annual Total Returns*

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Investor Class Prospectus Boston Partners Global Long/Short Fund		Average Annual Returns, 1 Year	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Institutional Class	[1]	1.40%	1.40%	Dec. 31, 2013
After Taxes on Distributions Institutional Class	[1][2]	1.40%	1.40%
After Taxes on Distributions and Sale of Fund Shares Institutional Class	[1]	0.79%	0.79%
MSCI® World Index (reflects no deduction for fees, expenses or taxes)	[1]	5.50%	5.50%	Dec. 31, 2013

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total Annual Fund Operating Expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.25% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total Annual Fund Operating Expenses (after fee waivers and expense reimbursements) are expected to exceed 2.25%. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time, the Fund's Total annual Fund operating expenses for that year are less than 2.25%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[1] The returns in the bar chart and table above are for Institutional Class shares, another class of shares of the Fund that is offered in a separate prospectus. Investor Class shares would have substantially similar annual returns because Investor Class shares are invested in the same portfolio of securities and the annual returns would differ only to the extent that the classes have different expenses.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Long/Short Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(2.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

2.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

2.25%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Dividend expense on short sales

rr_Component1OtherExpensesOverAssets

0.27%

^[1]

Interest expense on borrowings

rr_Component2OtherExpensesOverAssets

1.64%

Other operating expenses

rr_Component3OtherExpensesOverAssets

0.17%

Other expenses

rr_OtherExpensesOverAssets

2.08%

Total annual Fund operating expenses

rr_ExpensesOverAssets

4.58%

^[2]

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 65% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

65.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 459

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,383

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

2,314

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 4,677

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities.

Under normal circumstances, the Adviser expects that the Fund's long positions will not exceed approximately 125% of the Fund's net assets.

The Fund's long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Risk Lose Money [Text]

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Investors may lose money.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund's Investor Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Annual Return 2005

rr_AnnualReturn2005

16.98%

Annual Return 2006

rr_AnnualReturn2006

16.22%

Annual Return 2007

rr_AnnualReturn2007

(4.42%)

Annual Return 2008

rr_AnnualReturn2008

(21.33%)

Annual Return 2009

rr_AnnualReturn2009

80.92%

Annual Return 2010

rr_AnnualReturn2010

26.14%

Annual Return 2011

rr_AnnualReturn2011

5.63%

Annual Return 2012

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12.25%

Annual Return 2013

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7.59%

Annual Return 2014

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4.49%

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	38.45% (quarter ended June 30, 2009)
Worst Quarter:	(19.44)% (quarter ended December 31, 2008)

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

38.45%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

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(19.44%)

Performance Table Heading

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Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Caption

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Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.49%

Average Annual Returns, 5 Years

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10.95%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

12.01%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.30%

^[3]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

8.52%

^[3]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.15%

^[3]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.33%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

8.12%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

8.74%

S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

13.69%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

15.45%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.67%

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.75% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.75%.This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

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Risk/Return [Heading]

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Boston Partners Global Long/Short Fund

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Fund seeks long-term growth of capital.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

1.50%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Dividend expense on short sales

rr_Component1OtherExpensesOverAssets

1.06%

^[1]

Interest expense on borrowings

rr_Component2OtherExpensesOverAssets

0.85%

Other operating expenses

rr_Component3OtherExpensesOverAssets

1.48%

Other expenses

rr_OtherExpensesOverAssets

3.39%

^[2]

Total annual Fund operating expenses

rr_ExpensesOverAssets

4.89%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(1.01%)

^[2]

Net expenses

rr_NetExpensesOverAssets

3.88%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 72% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

72.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs of investing $100,000 in the Fund would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 3,902

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

13,802

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

23,724

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 48,626

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size. With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by Standard & Poor's Rating Group, or have a comparable rating by another nationally recognized statistical rating organization ("NRSRO") (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. The Fund will indirectly bear its proportionate share of any expenses, including management fees, paid by an externally managed REIT in which it invests.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Risk Lose Money [Text]

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Investors may lose money.

Risk Nondiversified Status [Text]

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The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the performance of the Boston Partners Global Long/Short Fund's Institutional Class. The bar chart below shows you how the Fund has performed on a calendar year basis and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below shows you how the Fund has performed on a calendar year basis and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Year Ended December 31

Annual Return 2014

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1.40%

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  0.89% (quarter ended September 30, 2014)

Worst Quarter:  (0.20)% (quarter ended December 31, 2014)

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Sep. 30, 2014

Highest Quarterly Return

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0.89%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Dec. 31, 2014

Lowest Quarterly Return

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(0.20%)

Performance Table Heading

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Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Caption

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Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

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1.40%

Average Annual Returns, Since Inception

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1.40%

Average Annual Returns, Inception Date

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Dec. 31, 2013

After Taxes on Distributions

Risk/Return:

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Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.40%

^[3]

Average Annual Returns, Since Inception

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1.40%

^[3]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

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Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.79%

Average Annual Returns, Since Inception

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0.79%

MSCI® World Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.50%

Average Annual Returns, Since Inception

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5.50%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 2.00% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.00%. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 2.00%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | Boston Partners Global Equity Fund | Institutional Class

Boston Partners Global Equity Fund

Investment Objective

The Fund seeks to provide long-term capital growth.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus Boston Partners Global Equity Fund Institutional Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus Boston Partners Global Equity Fund Institutional Class
Management fees		0.90%
Distribution (12b-1) fees		none
Other expenses		0.49%
Total annual Fund operating expenses		1.39%
Less Fee waivers and expense reimbursements	[1]	(0.44%)
Net expenses		0.95%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus Boston Partners Global Equity Fund Institutional Class	969	3,967	7,186	16,305

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 136% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer's inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. Redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Performance Information

The bar chart and table below illustrate the performance of the Boston Partners Global Equity Fund's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  11.70% (quarter ended March 31, 2012)

Worst Quarter:  (5.91)% (quarter ended June 30, 2012)

Average Annual Total Returns

Average Annual Total Returns (for the Periods Ended December 31, 2014)

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Institutional Class Prospectus Boston Partners Global Equity Fund		Average Annual Returns, 1 Year	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Institutional Class		4.34%	16.86%	Dec. 30, 2011
Institutional Class After Taxes on Distributions	[1]	2.69%	15.61%
Institutional Class After Taxes on Distributions and Sale of Fund Shares		2.75%	12.78%
Institutional Class MSCI World Index (reflects no deduction for fees, expenses or taxes)		5.50%	16.29%	Dec. 30, 2011

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.95% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.95%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 0.95%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year and since inception periods compare with those of a broad measure of market performance.

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Institutional Class Prospectus | Boston Partners All-Cap Value Fund | INSTITUTIONAL

Boston Partners All-Cap Value Fund

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus Boston Partners All-Cap Value Fund INSTITUTIONAL
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)	none
Exchange fee (as a percentage of amount exchanged on shares held for less than one year, if applicable)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus Boston Partners All-Cap Value Fund INSTITUTIONAL
Management fees		0.80%
Distribution (12b-1) fees		none
Other expenses		0.14%
Total annual Fund operating expenses		0.94%
Less Fee waivers and expense reimbursements	[1]	(0.24%)
Net expenses		0.70%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus Boston Partners All-Cap Value Fund INSTITUTIONAL	715	2,756	4,967	11,327

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 26% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 20% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small/Mid Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations.

Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 125%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  18.60% (quarter ended June 30, 2009)

Worst Quarter:  (17.49)% (quarter ended September 30, 2011)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Institutional Class Prospectus Boston Partners All-Cap Value Fund		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INSTITUTIONAL		12.23%	15.13%	9.72%
INSTITUTIONAL After Taxes on Distributions	[1]	10.45%	13.85%	8.44%
INSTITUTIONAL After Taxes on Distributions and Sale of Fund Shares		7.49%	11.76%	7.54%
INSTITUTIONAL Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)		12.70%	15.34%	7.26%

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.70% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.70%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Global Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital growth.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

0.90%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.49%

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.39%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.44%)

^[1]

Net expenses

rr_NetExpensesOverAssets

0.95%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 136% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

136.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 969

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

3,967

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

7,186

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 16,305

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer's inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. Redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the performance of the Boston Partners Global Equity Fund's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2012

rr_AnnualReturn2012

15.34%

Annual Return 2013

rr_AnnualReturn2013

32.67%

Annual Return 2014

rr_AnnualReturn2014

4.34%

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  11.70% (quarter ended March 31, 2012)

Worst Quarter:  (5.91)% (quarter ended June 30, 2012)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.70%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2012

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(5.91%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns (for the Periods Ended December 31, 2014)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.34%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

16.86%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.69%

^[2]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

15.61%

^[2]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.75%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

12.78%

MSCI World Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.50%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

16.29%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.95% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.95%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 0.95%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year and since inception periods compare with those of a broad measure of market performance.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Long/Short Research Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term total return.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

1.25%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Dividend expense on short sales

rr_Component1OtherExpensesOverAssets

0.84%

^[1]

Interest expense on borrowings

rr_Component2OtherExpensesOverAssets

0.30%

Other operating expenses

rr_Component3OtherExpensesOverAssets

0.13%

Other expenses

rr_OtherExpensesOverAssets

1.27%

Total annual Fund operating expenses

rr_ExpensesOverAssets

2.52%

^[2]

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 57% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

57.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

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$ 2,551

Expense Example, with Redemption, 3 Years

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7,845

Expense Example, with Redemption, 5 Years

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13,405

Expense Example, with Redemption, 10 Years

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$ 28,556

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or "micro") cap companies, as well as other instruments that are convertible into equity securities. Selling securities short is a form of leverage. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts ("REITs"), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Fund may also invest in depositary receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as "junk bonds"). Fixed income securities in which the Fund will invest include those rated between AAA and D by a nationally recognized statistical rating organization ("NRSRO"), or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund's portfolio or investments will be insulated from market moves or effectively hedged against risk.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest up to 30% in exchange-traded funds to the extent permitted by the Investment Company Act of 1940 ("1940 Act") and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund's investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

Risk Lose Money [Text]

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Investors may lose money.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and table below illustrate the performance of the Boston Partners Long/Short Research Fund's Institutional Class. The bar chart below provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart below provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Annual Return 2011

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3.40%

Annual Return 2012

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13.37%

Annual Return 2013

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17.77%

Annual Return 2014

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7.15%

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  8.37% (quarter ended December 31, 2011)

Worst Quarter:  (9.89)% (quarter ended September 30, 2011)

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Dec. 31, 2011

Highest Quarterly Return

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8.37%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Sep. 30, 2011

Lowest Quarterly Return

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(9.89%)

Performance Table Heading

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Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Caption

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Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

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7.15%

Average Annual Returns, Since Inception

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11.38%

Average Annual Returns, Inception Date

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Sep. 30, 2010

After Taxes on Distributions

Risk/Return:

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Average Annual Returns, 1 Year

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6.82%

^[3]

Average Annual Returns, Since Inception

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11.11%

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After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

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Average Annual Returns, 1 Year

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4.32%

Average Annual Returns, Since Inception

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8.93%

S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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Average Annual Returns, 1 Year

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13.69%

Average Annual Returns, Since Inception

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17.36%

Average Annual Returns, Inception Date

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Sep. 30, 2010

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 1.50%. This contractual limitation is in effect until at least January 26, 2016 and may not be terminated without Board approval. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 1.50%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class

Boston Partners Global Long/Short Fund

Investment Objective

The Fund seeks long-term growth of capital.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus Boston Partners Global Long/Short Fund Institutional Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus Boston Partners Global Long/Short Fund Institutional Class
Management fees		1.50%
Distribution and servicing (12b-1) fees		none
Dividend expense on short sales	[1]	1.06%
Interest expense on borrowings		0.85%
Other operating expenses		1.48%
Total other expenses	[2]	3.39%
Total annual Fund operating expenses		4.89%
Less Fee waivers and expense reimbursements	[2]	(1.01%)
Net expenses		3.88%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs of investing $100,000 in the Fund would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus Boston Partners Global Long/Short Fund Institutional Class	3,902	13,802	23,724	48,626

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 72% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size. With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by Standard & Poor's Rating Group, or have a comparable rating by another nationally recognized statistical rating organization ("NRSRO") (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. The Fund will indirectly bear its proportionate share of any expenses, including management fees, paid by an externally managed REIT in which it invests.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Performance Information

The bar chart and table below illustrate the performance of the Boston Partners Global Long/Short Fund's Institutional Class. The bar chart below shows you how the Fund has performed on a calendar year basis and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Year Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  0.89% (quarter ended September 30, 2014)

Worst Quarter:  (0.20)% (quarter ended December 31, 2014)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Institutional Class Prospectus Boston Partners Global Long/Short Fund		Average Annual Returns, 1 Year	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Institutional Class		1.40%	1.40%	Dec. 31, 2013
Institutional Class After Taxes on Distributions	[1]	1.40%	1.40%
Institutional Class After Taxes on Distributions and Sale of Fund Shares		0.79%	0.79%
Institutional Class MSCI® World Index (reflects no deduction for fees, expenses or taxes)		5.50%	5.50%	Dec. 31, 2013

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class shares exceeds 2.00% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.00%. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 2.00%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | INSTITUTIONAL

WPG Partners Small/Micro Cap Value Fund

Investment Objective

The Fund seeks capital appreciation by investing primarily in common stocks, securities convertible into common stocks and in special situations.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus WPG Partners Small/Micro Cap Value Fund INSTITUTIONAL
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	2.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus WPG Partners Small/Micro Cap Value Fund INSTITUTIONAL
Management fees		0.80%
Distribution (12b-1) fees		none
Other expenses		0.55%
Total annual Fund operating expenses		1.35%
Less Fee waivers and expense reimbursements	[1]	(0.25%)
Net expenses		1.10%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus WPG Partners Small/Micro Cap Value Fund INSTITUTIONAL	1,121	3,771	6,903	15,791

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 75% of the average value of its portfolio.

Summary of Principal Investment Strategies

Currently, the Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in equity securities of U.S. companies that, at the time of purchase, have a market capitalization that is within the range of the market capitalization of issuers in the Russell 2000^® Value Index. As of November 30, 2014, the median market capitalization of the companies in the Russell 2000^® Value Index is $601 million and the largest stock is $4.6 billion. The Fund may invest in depository receipts and equity securities of foreign companies. Although the Fund invests primarily in common stocks, the Fund may invest in all types of equity and equity-related securities, including (without limitation):

•  Securities convertible into common stocks.

•  Shares of real estate investment trusts ("REITs").

•  Warrants and rights to purchase common stocks.

•  Preferred stocks.

•  Exchange traded limited partnerships.

Special Situations: The Fund may invest in companies that may experience unusual and possibly unique developments which may create a special opportunity for significant returns. Special situations include: significant technological improvements or important discoveries; reorganizations, recapitalizations or mergers; favorable resolutions of litigation; new management or material changes in company policies; and actual or potential changes in control of a company.

Strategies: The Adviser uses a value approach to select the Fund's investments. Using this investment style, the Adviser seeks securities selling at substantial discounts to their underlying values and then holds these securities until the market values reflect what the Adviser believes to be their intrinsic values. The Adviser employs a bottom-up strategy, focusing on undervalued industries that the Adviser believes are experiencing positive change. The Adviser then uses both qualitative and quantitative methods to assess a security's potential value. The portfolio managers managing the Fund meet with a multitude of companies annually to identify companies with increasing returns on capital in their core businesses which are selling at attractive valuations.

Factors the Adviser looks for in selecting investments include (without limitation):

•  Increasing returns on invested capital.

•  Companies who have demonstrated an ability to generate high return on invested capital (ROIC).

•  Companies which provide solid cash flows with appropriate capital.

•  Potential catalysts such as new products, cyclical upturns and changes in management.

•  Low market valuations relative to earnings forecast, book value, cash flow and sales.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

Summary of Principal Risks

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Small Cap Companies Risk. The small capitalization equity securities in which the Fund may invest will often be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Special Situations Risk. The Fund will seek to benefit from "special situations," such as mergers, reorganizations, or other unusual events expected to affect a particular issuer. There is a risk that the "special situation" might not occur or involve longer time frames than originally expected, which could have a negative impact on the price of the issuer's securities and fail to produce gains or produce a loss for the Fund.

•  Rights and Warrants Risk. The purchase of rights or warrants involves the risk that the Fund could lose the purchase value of a right or warrant if the right to subscribe to additional shares is not executed prior to the right's or warrant's expiration. Also, the purchase of rights and/or warrants involves the risk that the effective price paid for the right and/or warrant added to the subscription price of the related security may exceed the value of the subscribed security's market price such as when there is no movement in the level of the underlying security.

Performance Information

The bar chart and table below illustrate the long-term performance of the WPG Partners Small/Micro Cap Value Fund's Institutional Class. The performance for periods prior to April 29, 2005 represents the performance of the WPG Tudor Fund (the "Predecessor Fund").The Predecessor Fund began operations on September 11, 1985. On April 29, 2005, the Predecessor Fund was reorganized as a new portfolio of the Company. Prior to the reorganization, the Predecessor Fund offered only one class of shares. In connection with the reorganization, shareholders of the Predecessor Fund exchanged their shares for Institutional Class shares of the Fund.

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year to year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  28.51% (quarter ended June 30, 2009)

Worst Quarter:  (30.21)% (quarter ended December 31, 2008)

Average Annual Total Returns

Average Annual Total Returns (for the Periods Ended December 31, 2014)

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Institutional Class Prospectus WPG Partners Small/Micro Cap Value Fund		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INSTITUTIONAL		(3.62%)	13.32%	6.16%
INSTITUTIONAL After Taxes on Distributions	[1]	(7.73%)	11.82%	4.44%
INSTITUTIONAL After Taxes on Distributions and Sale of Fund Shares		(1.11%)	10.32%	4.43%
INSTITUTIONAL Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)		4.22%	14.26%	6.89%

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time during the three years from May 28, 2014 to May 28, 2017 the Fund's Advisory Agreement with the Adviser is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.10%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund during such three-year period.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year, five year, and ten year periods compare with those of a broad measure of market performance.

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Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Small Cap Value Fund II

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

1.00%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.23%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.13%)

^[1]

Net expenses

rr_NetExpensesOverAssets

1.10%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-12-31

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 16% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

16.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 1,121

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

3,639

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

6,500

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 14,650

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2014, the median market capitalization of this index was $601 million and the largest stock was $4.6 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 175%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Annual Return 2005

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7.78%

Annual Return 2006

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15.94%

Annual Return 2007

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(7.30%)

Annual Return 2008

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(34.67%)

Annual Return 2009

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49.39%

Annual Return 2010

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18.50%

Annual Return 2011

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(3.43%)

Annual Return 2012

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22.87%

Annual Return 2013

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34.74%

Annual Return 2014

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4.21%

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  29.32% (quarter ended June 30, 2009)

Worst Quarter:  (26.32)% (quarter ended December 31, 2008)

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Jun. 30, 2009

Highest Quarterly Return

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29.32%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Dec. 31, 2008

Lowest Quarterly Return

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(26.32%)

Performance Table Heading

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Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Caption

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Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

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4.21%

Average Annual Returns, 5 Years

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14.57%

Average Annual Returns, 10 Years

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8.36%

After Taxes on Distributions

Risk/Return:

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Average Annual Returns, 1 Year

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3.60%

^[2]

Average Annual Returns, 5 Years

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14.29%

^[2]

Average Annual Returns, 10 Years

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6.91%

^[2]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

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Average Annual Returns, 1 Year

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2.64%

Average Annual Returns, 5 Years

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11.63%

Average Annual Returns, 10 Years

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6.55%

Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.22%

Average Annual Returns, 5 Years

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14.26%

Average Annual Returns, 10 Years

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6.89%

[1] The Fund's investment adviser, Robeco Investment Management, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time during the three years from May 28, 2014 to May 28, 2017 the Fund's Advisory Agreement with the Adviser is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.10%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund during such three-year period.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Investor Class Prospectus | Boston Partners Long/Short Research Fund | Investor Class

Boston Partners Long/Short Research Fund

Investment Objective

The Fund seeks to provide long-term total return.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Investor Class Prospectus Boston Partners Long/Short Research Fund Investor Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	none

Annual Fund Operating Expenses (expenses that that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Investor Class Prospectus Boston Partners Long/Short Research Fund Investor Class
Management fees		1.25%
Distribution (12b-1) fees		0.25%
Dividend expense on short sales	[1]	0.84%
Interest expense on borrowings		0.30%
Other operating expenses		0.13%
Total other expenses		1.27%
Total annual Fund operating expenses	[2]	2.77%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Investor Class Prospectus Boston Partners Long/Short Research Fund Investor Class	280	859	1,464	3,099

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 57% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or "micro")-cap companies, as well as other instruments that are convertible into equity securities. Selling securities short is a form of leverage. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts ("REITs"), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Fund may also invest in depository receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as "junk bonds"). Fixed income securities in which the Fund will invest include those rated between AAA and D by a nationally recognized statistical rating organization ("NRSRO"), or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund's portfolio or investments will be insulated from market moves or effectively hedged against risk.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest up to 30% in exchange-traded funds to the extent permitted by the Investment Company Act of 1940 ("1940 Act") and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund's investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

Performance Information

The bar chart and table below illustrate the performance of the Boston Partners Long/Short Research Fund's Investor Class. The bar chart below provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	8.29% (quarter ended December 31, 2011)
Worst Quarter:	(9.91)% (quarter ended September 30, 2011)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Investor Class Prospectus Boston Partners Long/Short Research Fund		Average Annual Returns, 1 Year	Average Annual Returns, Since Inception
Investor Class		6.86%	10.52%
Investor Class After Taxes on Distributions	[1]	6.52%	10.23%
Investor Class After Taxes on Distributions and Sale of Fund Shares		4.16%	8.21%
Investor Class S&P 500® Index (reflects no deduction for fees, expenses or taxes)		13.69%	16.83%

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total Annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.75% of the average daily net assets attributable to the Fund's Investor Class shares. Because acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total Annual Fund Operating Expenses (after fee waivers and expense reimbursements) are expected to exceed 1.75%.This contractual limitation is in effect until at least January 26, 2016 and may not be terminated without Board approval. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 1.75%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | INSTITUTIONAL

Boston Partners Small Cap Value Fund II

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus Boston Partners Small Cap Value Fund II INSTITUTIONAL
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus Boston Partners Small Cap Value Fund II INSTITUTIONAL
Management fees		1.00%
Distribution (12b-1) fees		none
Other expenses		0.23%
Total annual Fund operating expenses		1.23%
Less Fee waivers and expense reimbursements	[1]	(0.13%)
Net expenses		1.10%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus Boston Partners Small Cap Value Fund II INSTITUTIONAL	1,121	3,639	6,500	14,650

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 16% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2014, the median market capitalization of this index was $601 million and the largest stock was $4.6 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 175%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  29.32% (quarter ended June 30, 2009)

Worst Quarter:  (26.32)% (quarter ended December 31, 2008)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Institutional Class Prospectus Boston Partners Small Cap Value Fund II		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INSTITUTIONAL		4.21%	14.57%	8.36%
INSTITUTIONAL After Taxes on Distributions	[1]	3.60%	14.29%	6.91%
INSTITUTIONAL After Taxes on Distributions and Sale of Fund Shares		2.64%	11.63%	6.55%
INSTITUTIONAL Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)		4.22%	14.26%	6.89%

[1] The Fund's investment adviser, Robeco Investment Management, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time during the three years from May 28, 2014 to May 28, 2017 the Fund's Advisory Agreement with the Adviser is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.10%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund during such three-year period.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Investor Class Prospectus | Boston Partners Long/Short Equity Fund | INVESTOR

Boston Partners Long/Short Equity Fund

Investment Objective

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Investor Class Prospectus Boston Partners Long/Short Equity Fund INVESTOR
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)	2.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than one year, if applicable)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Investor Class Prospectus Boston Partners Long/Short Equity Fund INVESTOR
Management fees		2.25%
Distribution and service (12b-1) fees		0.25%
Dividend expense on short sales	[1]	0.27%
Interest expense on borrowings		1.64%
Other operating expenses		0.17%
Total other expenses		2.08%
Total annual Fund operating expenses	[2]	4.58%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Investor Class Prospectus Boston Partners Long/Short Equity Fund INVESTOR	459	1,383	2,314	4,677

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 65% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities.

Under normal circumstances, the Adviser expects that the Fund's long positions will not exceed approximately 125% of the Fund's net assets.

The Fund's long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund's Investor Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	38.45% (quarter ended June 30, 2009)
Worst Quarter:	(19.44)% (quarter ended December 31, 2008)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Average Annual Returns Investor Class Prospectus Boston Partners Long/Short Equity Fund		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INVESTOR		4.49%	10.95%	12.01%
INVESTOR After Taxes on Distributions	[1]	2.30%	8.52%	9.15%
INVESTOR After Taxes on Distributions and Sale of Fund Shares		4.33%	8.12%	8.74%
INVESTOR S&P 500® Index (reflects no deduction for fees, expenses or taxes)		13.69%	15.45%	7.67%

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.75% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.75%.This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Long/Short Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(2.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

2.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

2.25%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Dividend expense on short sales

rr_Component1OtherExpensesOverAssets

0.27%

^[1]

Interest expense on borrowings

rr_Component2OtherExpensesOverAssets

1.64%

Other operating expenses

rr_Component3OtherExpensesOverAssets

0.17%

Other expenses

rr_OtherExpensesOverAssets

2.08%

Total annual Fund operating expenses

rr_ExpensesOverAssets

4.33%

^[2]

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 65% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

65.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 4,345

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

13,121

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

22,016

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 44,779

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities. Under normal circumstances, the Adviser expects that the Fund's long positions will not exceed approximately 125% of the Fund's net assets.

The Fund's long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2005

rr_AnnualReturn2005

17.26%

Annual Return 2006

rr_AnnualReturn2006

16.60%

Annual Return 2007

rr_AnnualReturn2007

(4.24%)

Annual Return 2008

rr_AnnualReturn2008

(21.15%)

Annual Return 2009

rr_AnnualReturn2009

82.37%

Annual Return 2010

rr_AnnualReturn2010

26.44%

Annual Return 2011

rr_AnnualReturn2011

5.92%

Annual Return 2012

rr_AnnualReturn2012

12.47%

Annual Return 2013

rr_AnnualReturn2013

7.90%

Annual Return 2014

rr_AnnualReturn2014

4.72%

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  38.60% (quarter ended June 30, 2009)

Worst Quarter:  (19.45)% (quarter ended December 31, 2008)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

38.60%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.45%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.72%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

11.22%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

12.35%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.66%

^[3]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

8.89%

^[3]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.56%

^[3]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.36%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

8.36%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.05%

S&P 500® Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

13.69%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

15.45%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.67%

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class exceeds 2.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.50%. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[3] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

WPG Partners Small/Micro Cap Value Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks capital appreciation by investing primarily in common stocks, securities convertible into common stocks and in special situations.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(2.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

2.00%

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.55%

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.35%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.25%)

^[1]

Net expenses

rr_NetExpensesOverAssets

1.10%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-12-31

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 75% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

75.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 1,121

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

3,771

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

6,903

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 15,791

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Currently, the Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in equity securities of U.S. companies that, at the time of purchase, have a market capitalization that is within the range of the market capitalization of issuers in the Russell 2000^® Value Index. As of November 30, 2014, the median market capitalization of the companies in the Russell 2000^® Value Index is $601 million and the largest stock is $4.6 billion. The Fund may invest in depository receipts and equity securities of foreign companies. Although the Fund invests primarily in common stocks, the Fund may invest in all types of equity and equity-related securities, including (without limitation):

•  Securities convertible into common stocks.

•  Shares of real estate investment trusts ("REITs").

•  Warrants and rights to purchase common stocks.

•  Preferred stocks.

•  Exchange traded limited partnerships.

Special Situations: The Fund may invest in companies that may experience unusual and possibly unique developments which may create a special opportunity for significant returns. Special situations include: significant technological improvements or important discoveries; reorganizations, recapitalizations or mergers; favorable resolutions of litigation; new management or material changes in company policies; and actual or potential changes in control of a company.

Strategies: The Adviser uses a value approach to select the Fund's investments. Using this investment style, the Adviser seeks securities selling at substantial discounts to their underlying values and then holds these securities until the market values reflect what the Adviser believes to be their intrinsic values. The Adviser employs a bottom-up strategy, focusing on undervalued industries that the Adviser believes are experiencing positive change. The Adviser then uses both qualitative and quantitative methods to assess a security's potential value. The portfolio managers managing the Fund meet with a multitude of companies annually to identify companies with increasing returns on capital in their core businesses which are selling at attractive valuations.

Factors the Adviser looks for in selecting investments include (without limitation):

•  Increasing returns on invested capital.

•  Companies who have demonstrated an ability to generate high return on invested capital (ROIC).

•  Companies which provide solid cash flows with appropriate capital.

•  Potential catalysts such as new products, cyclical upturns and changes in management.

•  Low market valuations relative to earnings forecast, book value, cash flow and sales.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Small Cap Companies Risk. The small capitalization equity securities in which the Fund may invest will often be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Special Situations Risk. The Fund will seek to benefit from "special situations," such as mergers, reorganizations, or other unusual events expected to affect a particular issuer. There is a risk that the "special situation" might not occur or involve longer time frames than originally expected, which could have a negative impact on the price of the issuer's securities and fail to produce gains or produce a loss for the Fund.

•  Rights and Warrants Risk. The purchase of rights or warrants involves the risk that the Fund could lose the purchase value of a right or warrant if the right to subscribe to additional shares is not executed prior to the right's or warrant's expiration. Also, the purchase of rights and/or warrants involves the risk that the effective price paid for the right and/or warrant added to the subscription price of the related security may exceed the value of the subscribed security's market price such as when there is no movement in the level of the underlying security.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the WPG Partners Small/Micro Cap Value Fund's Institutional Class. The performance for periods prior to April 29, 2005 represents the performance of the WPG Tudor Fund (the "Predecessor Fund").The Predecessor Fund began operations on September 11, 1985. On April 29, 2005, the Predecessor Fund was reorganized as a new portfolio of the Company. Prior to the reorganization, the Predecessor Fund offered only one class of shares. In connection with the reorganization, shareholders of the Predecessor Fund exchanged their shares for Institutional Class shares of the Fund.

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year to year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the performance of the Fund's Institutional Class has varied year to year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2005

rr_AnnualReturn2005

(2.00%)

Annual Return 2006

rr_AnnualReturn2006

23.38%

Annual Return 2007

rr_AnnualReturn2007

(7.04%)

Annual Return 2008

rr_AnnualReturn2008

(38.73%)

Annual Return 2009

rr_AnnualReturn2009

41.23%

Annual Return 2010

rr_AnnualReturn2010

26.10%

Annual Return 2011

rr_AnnualReturn2011

(11.95%)

Annual Return 2012

rr_AnnualReturn2012

22.88%

Annual Return 2013

rr_AnnualReturn2013

42.08%

Annual Return 2014

rr_AnnualReturn2014

(3.62%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  28.51% (quarter ended June 30, 2009)

Worst Quarter:  (30.21)% (quarter ended December 31, 2008)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

28.51%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(30.21%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns (for the Periods Ended December 31, 2014)

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(3.62%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

13.32%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.16%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(7.73%)

^[2]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

11.82%

^[2]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

4.44%

^[2]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

(1.11%)

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

10.32%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

4.43%

Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.22%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

14.26%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.89%

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 1.10% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.10%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time during the three years from May 28, 2014 to May 28, 2017 the Fund's Advisory Agreement with the Adviser is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.10%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund during such three-year period.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year, five year, and ten year periods compare with those of a broad measure of market performance.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Jan. 26, 2015

XML

Document and Entity Information	0 Months Ended
	Aug. 31, 2015
Risk/Return:
Document Type	485BPOS
Document Period End Date	Aug. 31, 2015
Registrant Name	RBB FUND INC
Central Index Key	0000831114
Amendment Flag	false
Document Creation Date	Jan. 26, 2015
Document Effective Date	Jan. 26, 2015
Prospectus Date	Jan. 26, 2015
Institutional Class Prospectus | Boston Partners Small Cap Value Fund II | INSTITUTIONAL
Risk/Return:
Trading Symbol	BPSIX
Institutional Class Prospectus | Boston Partners All-Cap Value Fund | INSTITUTIONAL
Risk/Return:
Trading Symbol	BPAIX
Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | INSTITUTIONAL
Risk/Return:
Trading Symbol	BPLSX
Institutional Class Prospectus | Boston Partners Long/Short Research Fund | Institutional Class
Risk/Return:
Trading Symbol	BPIRX
Institutional Class Prospectus | WPG Partners Small/Micro Cap Value Fund | INSTITUTIONAL
Risk/Return:
Trading Symbol	WPGTX
Institutional Class Prospectus | Boston Partners Global Equity Fund | Institutional Class
Risk/Return:
Trading Symbol	BPGIX
Institutional Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class
Risk/Return:
Trading Symbol	BGLSX
Investor Class Prospectus | Boston Partners Small Cap Value Fund II | INVESTOR
Risk/Return:
Trading Symbol	BPSCX
Investor Class Prospectus | Boston Partners All-Cap Value Fund | INVESTOR
Risk/Return:
Trading Symbol	BPAVX
Investor Class Prospectus | Boston Partners Long/Short Equity Fund | INVESTOR
Risk/Return:
Trading Symbol	BPLEX
Investor Class Prospectus | Boston Partners Long/Short Research Fund | Investor Class
Risk/Return:
Trading Symbol	BPRRX
Investor Class Prospectus | Boston Partners Global Equity Fund | Institutional Class
Risk/Return:
Trading Symbol	BPGIX
Investor Class Prospectus | Boston Partners Global Equity Fund | Investor Class
Risk/Return:
Trading Symbol	BPGRX
Investor Class Prospectus | Boston Partners Global Long/Short Fund | Institutional Class
Risk/Return:
Trading Symbol	BGLSX
Investor Class Prospectus | Boston Partners Global Long/Short Fund | Investor Class
Risk/Return:
Trading Symbol	BGRSX

XML

Institutional Class Prospectus | Boston Partners Long/Short Research Fund | Institutional Class

Boston Partners Long/Short Research Fund

Investment Objective

The Fund seeks to provide long-term total return.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus Boston Partners Long/Short Research Fund Institutional Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus Boston Partners Long/Short Research Fund Institutional Class
Management fees		1.25%
Distribution (12b-1) fees		none
Dividend expense on short sales	[1]	0.84%
Interest expense on borrowings		0.30%
Other operating expenses		0.13%
Total other expenses		1.27%
Total annual Fund operating expenses	[2]	2.52%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus Boston Partners Long/Short Research Fund Institutional Class	2,551	7,845	13,405	28,556

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 57% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund uses a hedged strategy. The Fund actively invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales (i.e. sales of securities the Fund does not own) will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate.

The Fund invests, both long and short, in equity securities issued by large-, mid- and small (or "micro") cap companies, as well as other instruments that are convertible into equity securities. Selling securities short is a form of leverage. Equity securities in which the Fund may invest include exchange-traded and over-the-counter common and preferred stocks, warrants, rights, convertible securities, depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies and real estate investment trusts ("REITs"), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Fund may also invest in depositary receipts and equity securities of foreign companies (denominated in either U.S. dollars or foreign currencies), put and call options, futures, indexed securities and fixed-income securities (including bonds, notes, asset-backed securities, convertible securities, Eurodollar and Yankee dollar instruments, preferred stocks and money market instruments) and high yield securities (commonly referred to as "junk bonds"). Fixed income securities in which the Fund will invest include those rated between AAA and D by a nationally recognized statistical rating organization ("NRSRO"), or deemed of comparable quality by the Adviser. The Adviser may also temporarily invest uninvested cash in money market funds and similar collective investment vehicles. The Fund may also seek to increase its income by lending portfolio securities.

The Adviser determines the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the U.S. equity market by investing less than 100% of its assets in net long positions. Selection of individual securities to be held long or sold short will be based on a mix of quantitative techniques and fundamental security analysis. The Adviser selects stocks on the basis of three criteria: value, fundamental business strength and momentum. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

Although the Fund seeks to follow a hedged strategy, there can be no assurance that the Fund's portfolio or investments will be insulated from market moves or effectively hedged against risk.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry, except that the Fund may invest up to 30% in exchange-traded funds to the extent permitted by the Investment Company Act of 1940 ("1940 Act") and applicable SEC orders.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The principal derivative instruments in which the Fund invests are futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps. The Fund's investments in derivative instruments may be leveraged and result in losses exceeding the amounts invested.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the price of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations (of any rating, including defaulted securities and unrated securities), including bonds and debentures, issued by corporations and business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and financial practices.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Management Risk. The Fund is subject to the risk of poor stock selection. The Adviser may be incorrect in the stocks it buys and believes to be undervalued and in stocks it sells short and believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 300%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  Indexed Securities Risk. The Fund may invest in indexed securities whose value is linked to securities indices. Most such securities have values that rise and fall according to the change in one or more specified indices and may have characteristics similar to direct investments in the underlying securities. Depending on the index, such securities may have greater volatility than the market as a whole.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

Performance Information

The bar chart and table below illustrate the performance of the Boston Partners Long/Short Research Fund's Institutional Class. The bar chart below provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  8.37% (quarter ended December 31, 2011)

Worst Quarter:  (9.89)% (quarter ended September 30, 2011)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Institutional Class Prospectus Boston Partners Long/Short Research Fund		Average Annual Returns, 1 Year	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Institutional Class		7.15%	11.38%	Sep. 30, 2010
Institutional Class After Taxes on Distributions	[1]	6.82%	11.11%
Institutional Class After Taxes on Distributions and Sale of Fund Shares		4.32%	8.93%
Institutional Class S&P 500® Index (reflects no deduction for fees, expenses or taxes)		13.69%	17.36%	Sep. 30, 2010

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to forgo all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) exceeds 1.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 1.50%. This contractual limitation is in effect until at least January 26, 2016 and may not be terminated without Board approval. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 1.50%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners All-Cap Value Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

none

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.14%

Total annual Fund operating expenses

rr_ExpensesOverAssets

0.94%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.24%)

^[1]

Net expenses

rr_NetExpensesOverAssets

0.70%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 26% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

26.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 715

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

2,756

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

4,967

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 11,327

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may also invest up to 20% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small/Mid Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations.

Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 125%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2005

rr_AnnualReturn2005

9.88%

Annual Return 2006

rr_AnnualReturn2006

17.63%

Annual Return 2007

rr_AnnualReturn2007

1.47%

Annual Return 2008

rr_AnnualReturn2008

(27.26%)

Annual Return 2009

rr_AnnualReturn2009

30.97%

Annual Return 2010

rr_AnnualReturn2010

13.42%

Annual Return 2011

rr_AnnualReturn2011

(1.38%)

Annual Return 2012

rr_AnnualReturn2012

15.83%

Annual Return 2013

rr_AnnualReturn2013

39.12%

Annual Return 2014

rr_AnnualReturn2014

12.23%

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  18.60% (quarter ended June 30, 2009)

Worst Quarter:  (17.49)% (quarter ended September 30, 2011)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

18.60%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.49%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

12.23%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

15.13%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.72%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

10.45%

^[2]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

13.85%

^[2]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

8.44%

^[2]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

7.49%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

11.76%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.54%

Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

12.70%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

15.34%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.26%

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Institutional Class shares exceeds 0.70% of the average daily net assets attributable to the Fund's Institutional Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.70%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Institutional Class Prospectus | Boston Partners Long/Short Equity Fund | INSTITUTIONAL

Boston Partners Long/Short Equity Fund

Investment Objective

The Fund seeks long-term capital appreciation while reducing exposure to general equity market risk. The Fund seeks a total return greater than that of the S&P 500^® Index over a full market cycle.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Institutional Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Class Prospectus Boston Partners Long/Short Equity Fund INSTITUTIONAL
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)	2.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than one year, if applicable)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Institutional Class Prospectus Boston Partners Long/Short Equity Fund INSTITUTIONAL
Management fees		2.25%
Distribution (12b-1) fees		none
Dividend expense on short sales	[1]	0.27%
Interest expense on borrowings		1.64%
Other operating expenses		0.17%
Total other expenses		2.08%
Total annual Fund operating expenses	[2]	4.33%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $100,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Class Prospectus Boston Partners Long/Short Equity Fund INSTITUTIONAL	4,345	13,121	22,016	44,779

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 65% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities principally traded in the United States markets. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Fund seeks to construct a portfolio that has less volatility than the United States equity market generally. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund intends, under normal circumstances, to invest at least 80% of its net assets (including borrowings for investment purposes) in equity securities. Under normal circumstances, the Adviser expects that the Fund's long positions will not exceed approximately 125% of the Fund's net assets.

The Fund's long and short positions may involve (without limit) equity securities of foreign issuers that are traded in the markets of the United States. The Fund may also invest up to 20% of its total assets directly in equity securities of foreign issuers.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by corporations and other business organizations.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Long/Short Equity Fund's Institutional Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:  38.60% (quarter ended June 30, 2009)

Worst Quarter:  (19.45)% (quarter ended December 31, 2008)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods. Although the Fund compares its average total return to a broad-based securities market index, the Fund seeks returns that are not correlated to securities market returns. The Fund seeks to achieve a 12-15% return over a full market cycle; however, there can be no guarantee that such returns will be achieved.

Average Annual Returns Institutional Class Prospectus Boston Partners Long/Short Equity Fund		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INSTITUTIONAL		4.72%	11.22%	12.35%
INSTITUTIONAL After Taxes on Distributions	[1]	2.66%	8.89%	9.56%
INSTITUTIONAL After Taxes on Distributions and Sale of Fund Shares		4.36%	8.36%	9.05%
INSTITUTIONAL S&P 500® Index (reflects no deduction for fees, expenses or taxes)		13.69%	15.45%	7.67%

[1] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[2] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Institutional Class exceeds 2.50% of the average daily net assets attributable to the Fund's Institutional Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total annual Fund operating expenses (after fee waivers and expense reimbursements) are expected to exceed 2.50%. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners All-Cap Value Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

Current income is a secondary objective.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

none

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management fees

rr_ManagementFeesOverAssets

0.80%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.14%

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.19%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.24%)

^[1]

Net expenses

rr_NetExpensesOverAssets

0.95%

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 26% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

26.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 97

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

354

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

631

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,422

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 20% of its total assets in non U.S. dollar denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

rr_RiskHeading

Summary of Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 125%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund's Investor Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

rr_BarChartHeading

Total Returns for the Calendar Years Ended December 31

Annual Return 2005

rr_AnnualReturn2005

9.57%

Annual Return 2006

rr_AnnualReturn2006

17.41%

Annual Return 2007

rr_AnnualReturn2007

1.23%

Annual Return 2008

rr_AnnualReturn2008

(27.56%)

Annual Return 2009

rr_AnnualReturn2009

30.77%

Annual Return 2010

rr_AnnualReturn2010

13.19%

Annual Return 2011

rr_AnnualReturn2011

(1.62%)

Annual Return 2012

rr_AnnualReturn2012

15.61%

Annual Return 2013

rr_AnnualReturn2013

38.92%

Annual Return 2014

rr_AnnualReturn2014

11.98%

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	18.56% (quarter ended June 30, 2009)
Worst Quarter:	(17.62)% (quarter ended September 30, 2011)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

18.56%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.62%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns for the Periods Ended December 31, 2014

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

11.98%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

14.90%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.46%

After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

10.30%

^[2]

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

13.71%

^[2]

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

8.28%

^[2]

After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

7.35%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

11.61%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.37%

Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

12.70%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

15.34%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.26%

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 0.95% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.95%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Boston Partners Global Equity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide long-term capital growth.

Expense [Heading]

rr_ExpenseHeading

Expenses and Fees

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund's Institutional Class was 136% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

136.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a non-diversified portfolio of equity and equity-related securities issued by U.S. and non-U.S. companies of any capitalization size. The Fund may invest in all types of equity and equity- related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, participatory notes, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")) and real estate investment trusts ("REITs"), and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund generally invests in the equity securities of issuers believed by the Adviser to be undervalued in the marketplace, focusing on issuers that combine attractive valuations with catalysts for change. The Adviser applies a bottom-up stock selection process (i.e., one that focuses primarily on issuer-specific factors) in managing the Fund, using a combination of fundamental and quantitative analysis. In selecting investments for the Fund, the Adviser considers various factors such as price-to-book value, price-to-sales and earnings ratios, dividend yields, strength of management, and cash flow to identify securities that are trading at a price that appears to be lower than the issuer's inherent value.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO").An IPO is a company's first offering of stock to the public. The Fund may also seek to increase its income by lending portfolio securities.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index.

•  Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. Redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker- dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Risk Lose Money [Text]

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Investors may lose money.

Risk Nondiversified Status [Text]

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The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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As of the date of this Prospectus, the Boston Partners Global Equity Fund's Investor Class has not yet commenced operations. The bar chart and table below illustrate the performance of the Fund's Institutional Class, which is offered in a separate Prospectus. Had the Investor Class been operational during the periods in the chart and table below, it would have had substantially similar annual returns as the Institutional Class because the Investor Class is invested in the same portfolio of securities. Annual returns would differ only to the extent that the Investor Class and Institutional Class do not have the same expenses. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risk of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

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The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year and since inception periods compare with those of a broad measure of market performance.

Performance One Year or Less [Text]

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As of the date of this Prospectus, the Boston Partners Global Equity Fund's Investor Class has not yet commenced operations.

Performance Availability Phone [Text]

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1-888-261-4073

Performance Availability Website Address [Text]

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www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Years Ended December 31

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	11.70% (quarter ended March 31, 2012)
Worst Quarter:	(5.91)% (quarter ended June 30, 2012)

Bar Chart, Returns for Class Not Offered in Prospectus [Text]

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The bar chart and table below illustrate the performance of the Fund's Institutional Class, which is offered in a separate Prospectus.

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Mar. 31, 2012

Highest Quarterly Return

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11.70%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Jun. 30, 2012

Lowest Quarterly Return

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(5.91%)

Performance Table Heading

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Average Annual Total Returns

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Caption

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Average Annual Total Returns for the Period Ended December 31, 2014

MSCI World Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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Average Annual Returns, 1 Year

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5.50%

Average Annual Returns, Since Inception

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16.29%

Average Annual Returns, Inception Date

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Dec. 30, 2011

Investor Class

Risk/Return:

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Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

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none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Management fees

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0.90%

Distribution (12b-1) fees

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0.25%

Other expenses

rr_OtherExpensesOverAssets

0.49%

Total annual Fund operating expenses

rr_ExpensesOverAssets

1.64%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.44%)

^[1]

Net expenses

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1.20%

Expense Example, with Redemption, 1 Year

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122

Expense Example, with Redemption, 3 Years

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474

Expense Example, with Redemption, 5 Years

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850

Expense Example, with Redemption, 10 Years

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1,907

Institutional Class

Risk/Return:

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Annual Return 2012

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15.34%

Annual Return 2013

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32.67%

Annual Return 2014

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4.34%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

4.34%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

16.86%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 2011

Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.69%

^[2]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

15.61%

^[2]

Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

2.75%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

12.78%

[1] The Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.20% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.20%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time the Fund's Total annual Fund operating expenses for that year are less than 1.20%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[2] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The table, like the bar chart, provides some indication of the risks of investing in the Fund by showing how the Fund's average annual total returns for the one year and since inception periods compare with those of a broad measure of market performance.

XML

Label

Element

Value

Risk/Return:

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Risk/Return [Heading]

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Boston Partners Global Long/Short Fund

Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The Fund seeks long-term growth of capital.

Expense [Heading]

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Expenses and Fees

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2016-01-26

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total annual Fund operating expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 72% of the average value of its portfolio.

Portfolio Turnover, Rate

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72.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and Fund operating expenses remain the same. Although your actual costs and returns might be different, based on these assumptions your costs of investing $10,000 in the Fund would be:

Strategy [Heading]

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Summary of Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund invests in long positions in stocks identified by the Adviser as undervalued and takes short positions in stocks that the Adviser has identified as overvalued. The cash proceeds from short sales will be invested in short-term cash instruments to produce a return on such proceeds just below the federal funds rate. The Fund will invest, both long and short, in securities issued by U.S. and non-U.S. companies of any capitalization size.

With a long position, the Fund purchases a stock outright; with a short position, the Fund sells a security that it does not own and must borrow to meet its settlement obligations. The Fund may invest in securities of companies operating for three years or less ("unseasoned issuers"). The Adviser will determine the size of each long or short position by analyzing the tradeoff between the attractiveness of each position and its impact on the risk of the overall portfolio. The Adviser examines various factors in determining the value characteristics of such issuers including price-to-book value ratios and price-to-earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, including return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may invest in all types of equity and equity-related securities, including without limitation exchange-traded and over-the-counter common and preferred stocks, warrants, options, rights, convertible securities, sponsored and unsponsored depositary receipts and shares, trust certificates, limited partnership interests, shares of other investment companies (including exchanged-traded funds ("ETFs")), real estate investment trusts ("REITs") and equity participations. An equity participation is a type of loan that gives the lender a portion of equity ownership in a property, in addition to principal and interest payments. A convertible security is a bond, debenture, note, preferred stock or other security that may be converted into or exchanged for a prescribed amount of common stock of the same or a different issuer within a particular period of time at a specified price or formula.

The Fund defines non-U.S. companies as companies (i) that are organized under the laws of a foreign country; (ii) whose principal trading market is in a foreign country; or (iii) that have a majority of their assets, or that derive a significant portion of their revenue or profits from businesses, investments or sales, outside of the United States. Under normal market conditions, the Fund invests significantly (ordinarily at least 40% — unless market conditions are not deemed favorable by the Adviser, in which case the Fund would invest at least 30%) in non-U.S. companies. The Fund principally will be invested in issuers located in countries with developed securities markets, but may also invest in issuers located in emerging markets. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund's portfolio is rebalanced regularly. The Adviser assesses each investment's changing characteristics relative to its contribution to portfolio risk. The Adviser will sell an investment held long or close out a short position that the Adviser believes no longer offers an appropriate return-to-risk tradeoff.

Under normal circumstances, the Adviser expects to sell securities short so that the Fund's portfolio is approximately 50% net long with an average of between 30% and 70% net long.

To meet margin requirements, redemptions or pending investments, the Fund may also temporarily hold a portion of its assets in full faith and credit obligations of the United States government and in short-term notes, commercial paper or other money market instruments.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest from time to time a significant portion of its assets in smaller issuers which are more volatile and less liquid than investments in issuers with larger market capitalizations.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, used by U.S. and foreign corporations and other business organizations (e.g. trusts or limited liability companies). Such high yield debt obligations are not considered to be investment grade. Non-investment grade fixed income securities (commonly known as "junk bonds") are rated BB or lower by Standard & Poor's Rating Group, or have a comparable rating by another nationally recognized statistical rating organization ("NRSRO") (or, if unrated are determined by the Adviser to be of comparable quality at the time of investment). The Fund may invest in securities of the lowest rating category, including securities in default. The Adviser may, but is not required to, sell a bond or note held by the Fund in the event that its credit rating is downgraded.

The Fund may (but is not required to) invest in derivatives, including put and call options, futures, forward contracts and swaps, in lieu of investing directly in a security, currency or instrument, for hedging and non-hedging purposes.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Risk [Heading]

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Summary of Principal Risks

Risk Narrative [Text Block]

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•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the Adviser may not be successful in its strategy of taking long positions in stocks the manager believes to be undervalued and short positions in stocks the manager believes to be overvalued. Further, since the Adviser will manage both a long and a short portfolio, there is the risk that the Adviser may make more poor investment decisions than an adviser of a typical stock mutual fund with only a long portfolio may make.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the long portfolio of the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  High Yield Debt Obligations Risk. The Fund may invest up to 20% of its net assets in high yield debt obligations, such as bonds and debentures, issued by corporations and other business organizations. An issuer of debt obligations may default on its obligation to pay interest and repay principal. Also, changes in the financial strength of an issuer or changes in the credit rating of a security may affect its value. Such high yield debt obligations are referred to as "junk bonds" and are not considered to be investment grade.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices. The Fund may invest in securities of foreign issuers either directly or through depositary receipts. Depositary receipts may be available through "sponsored" or "unsponsored" facilities. Holders of unsponsored depositary receipts generally bear all of the costs of the unsponsored facility. The depository of an unsponsored facility is frequently under no obligation to distribute shareholder communications received from the issuer of the deposited security or to pass through, to the holders of the receipts, voting rights with respect to the deposited securities. The depository of unsponsored depositary receipts may provide less information to receipt holders. Participatory notes ("P-notes") are derivative instruments used by investors to take positions in certain foreign securities. P-notes present similar risks to investing directly in such securities and also expose investors to counterparty risk.

•  Emerging Markets Risk. Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers.

•  Currency Risk. Investment in foreign securities also involves currency risk associated with securities that trade or are denominated in currencies other than the U.S. dollar and which may be affected by fluctuations in currency exchange rates. An increase in the strength of the U.S. dollar relative to a foreign currency may cause the U.S. dollar value of an investment in that country to decline. Foreign currencies also are subject to risks caused by inflation, interest rates, budget deficits and low savings rates, political factors and government controls.

•  Short Sales Risk. Short sales of securities may result in gains if a security's price declines, but may result in losses if a security's price rises. In a rising market, short positions may be more likely to result in losses because securities sold short may be more likely to increase in value. Short selling also involves the risks of: increased leverage, and its accompanying potential for losses; the potential inability to reacquire a security in a timely manner, or at an acceptable price; the possibility of the lender terminating the loan at any time, forcing the Fund to close the transaction under unfavorable circumstances; the additional costs that may be incurred; and the potential loss of investment flexibility caused by the Fund's obligations to provide collateral to the lender and set aside assets to cover the open position. Short sales "against the box" may protect the Fund against the risk of losses in the value of a portfolio security because any decline in value of the security should be wholly or partially offset by a corresponding gain in the short position. Any potential gains in the security, however, would be wholly or partially offset by a corresponding loss in the short position. Short sales that are not "against the box" involve a form of investment leverage, and the amount of the Fund's loss on a short sale is potentially unlimited. The use of short sales may cause the Fund to have higher expenses than those of other equity mutual funds because of higher transaction costs, premiums, interest or dividends payable to the lender.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations. Losses incurred by the Fund in writing options can be potentially unlimited.

•  Derivatives Risk. The Fund's investments in derivative instruments, which include futures and options on securities, securities indices or currencies, options on these futures, forward foreign currency contracts and interest rate or currency swaps, may be leveraged and result in losses exceeding the amounts invested.

•  REITs Risk. REITs may be affected by economic forces and other factors related to the real estate industry. Investing in REITs may involve risks similar to those associated with investing in small capitalization companies. REITs may have limited financial resources, may trade less frequently and in a limited volume and may be subject to more abrupt or erratic price movements than larger company securities. Historically, small capitalization stocks, such as REITs, have been more volatile in price than the larger capitalization stocks included in the S&P 500^® Index. The Fund will indirectly bear its proportionate share of any expenses, including management fees, paid by an externally managed REIT in which it invests.

•  Unseasoned Issuers Risk. Unseasoned issuers may not have an established financial history and may have limited product lines, markets or financial resources. Unseasoned issuers may depend on a few key personnel for management and may be susceptible to losses and risks of bankruptcy. As a result, such securities may be more volatile and difficult to sell.

•  Small-Cap Companies Risk. The small capitalization equity securities in which the Fund may invest may be traded only in the over-the-counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 400%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Segregated Account Risk. A security held in a segregated account cannot be sold while the position it is covering is outstanding, unless it is replaced with a similar security. As a result, there is a possibility that segregation of a large percentage of the Fund's assets could impede portfolio management or the Fund's ability to meet redemption requests or other current obligations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

•  Securities Lending Risk. The Fund may lend portfolio securities to institutions, such as certain broker-dealers. The Fund may experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.

•  Exchange Traded Fund Risk. Exchange traded funds ("ETFs") are a type of investment company bought and sold on a securities exchange. An ETF represents a fixed portfolio of securities designed to track a particular market index. The risks of owning an ETF generally reflect the risks of owning the underlying securities that they are designed to track, although lack of liquidity in an ETF could result in its being more volatile. The Fund may incur brokerage fees in connection with its purchase of ETF shares.

•  Non-Diversification Risk. The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

Investors may lose money.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified. Compared to other funds, the Fund may invest more of its assets in a smaller number of companies. Gains or losses on a single stock may have greater impact on the Fund.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The Investor Class commenced operations on April 11, 2014, therefore annual returns for one full calendar year are not available for Investor Class shares of the Fund. The bar chart and table below illustrate the performance of the Boston Partners Global Long/Short Fund's Institutional Class, another class of shares of the Fund that is offered in a separate prospectus. The bar chart below shows you how Institutional Class shares of the Fund have performed on a calendar year basis and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart below shows you how Institutional Class shares of the Fund have performed on a calendar year basis and provides some indication of the risks of investing in the Fund.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

The Investor Class commenced operations on April 11, 2014, therefore annual returns for one full calendar year are not available for Investor Class shares of the Fund.

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

1-888-261-4073

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.boston-partners.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Total Returns for the Calendar Year Ended December 31 (Institutional Class)*

Bar Chart Closing [Text Block]

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Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	0.89% (quarter ended September 30, 2014)
Worst Quarter:	(0.20)% (quarter ended December 31, 2014)

Bar Chart, Returns for Class Not Offered in Prospectus [Text]

rr_BarChartReturnsForClassNotOfferedInProspectus

The bar chart and table below illustrate the performance of the Boston Partners Global Long/Short Fund's Institutional Class, another class of shares of the Fund that is offered in a separate prospectus.

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2014

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.89%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2014

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(0.20%)

Performance Table Heading

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Average Annual Total Returns*

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Narrative

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The table below compares the average annual total returns for the Fund's Institutional Class both before and after taxes for the past calendar year and since inception to the average annual total returns of a broad-based securities market index for the same periods.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns for the Periods Ended December 31, 2014

MSCI® World Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.50%

^[1]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.50%

^[1]

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

^[1]

Investor Class

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum sales charge (load) imposed on reinvested dividends

rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther

none

Redemption fee (as a percentage of amount redeemed on shares held for less than one year, if applicable)

rr_RedemptionFeeOverRedemption

(1.00%)

Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)

rr_ExchangeFeeOverRedemption

1.00%

Management fees

rr_ManagementFeesOverAssets

1.50%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Dividend expense on short sales

rr_Component1OtherExpensesOverAssets

1.06%

^[2]

Interest expense on borrowings

rr_Component2OtherExpensesOverAssets

0.85%

Other operating expenses

rr_Component3OtherExpensesOverAssets

1.48%

Other expenses

rr_OtherExpensesOverAssets

3.39%

Total annual Fund operating expenses

rr_ExpensesOverAssets

5.14%

Less Fee waivers and expense reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(1.01%)

^[3]

Net expenses

rr_NetExpensesOverAssets

4.13%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

414

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,450

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

2,483

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

5,052

Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Annual Return 2014

rr_AnnualReturn2014

1.40%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.40%

^[1]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

1.40%

^[1]

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2013

^[1]

Institutional Class | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.40%

^[1],[4]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

1.40%

^[1],[4]

Institutional Class | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

0.79%

^[1]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

0.79%

^[1]

[1] The returns in the bar chart and table above are for Institutional Class shares, another class of shares of the Fund that is offered in a separate prospectus. Investor Class shares would have substantially similar annual returns because Investor Class shares are invested in the same portfolio of securities and the annual returns would differ only to the extent that the classes have different expenses.

[2] There are additional costs associated with the use of short sales. Short-sale dividends generally reduce the market value of the securities by the amount of the dividend declared; thus increasing the Fund's unrealized gain or reducing the Fund's unrealized loss on the securities sold short.

[3] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total Annual Fund Operating Expenses (other than acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes) for the Fund's Investor Class shares exceeds 2.25% of the average daily net assets attributable to the Fund's Investor Class shares. Because dividend expenses on short sales, acquired fund fees and expenses, brokerage commissions, extraordinary items, interest and taxes are excluded from the expense limitation, Total Annual Fund Operating Expenses (after fee waivers and expense reimbursements) are expected to exceed 2.25%. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. Effective as of the effective date of the Fund's first advisory agreement with the Adviser, if at any time, the Fund's Total annual Fund operating expenses for that year are less than 2.25%, the Adviser is entitled to reimbursement by the Fund of the advisory fees waived and other payments remitted by the Adviser to the Fund within three years from the date on which such waiver or reimbursement was made.

[4] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Investor Class Prospectus | Boston Partners Small Cap Value Fund II | INVESTOR

Boston Partners Small Cap Value Fund II

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Investor Class Prospectus Boston Partners Small Cap Value Fund II INVESTOR
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed on shares held for less than 60 days, if applicable)	1.00%
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	1.00%

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Investor Class Prospectus Boston Partners Small Cap Value Fund II INVESTOR
Management fees		1.00%
Distribution and servicing (12b-1) fees		0.25%
Other expenses		0.23%
Total annual Fund operating expenses		1.48%
Less Fee waivers and expense reimbursements	[1]	(0.13%)
Net expenses		1.35%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Investor Class Prospectus Boston Partners Small Cap Value Fund II INVESTOR	137	428	769	1,733

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 16% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers with small market capitalizations and identified by the Adviser as having value characteristics. A small market capitalization issuer generally is considered to be one whose market capitalization is, at the time the Fund makes the investment, similar to the market capitalization of companies in the Russell 2000^® Value Index. The Russell 2000^® Value Index is an unmanaged index that contains stocks from the Russell 2000^® Index with less than average growth orientation. As of November 30, 2014, the median market capitalization of this index was $601 million and the largest stock was $4.6 billion. Please note that this range is as of a particular point in time and is subject to change.

The Fund generally invests in the equity securities of small companies. The Adviser will seek to invest in companies it considers to be well managed and to have attractive fundamental financial characteristics. The Adviser believes greater potential for price appreciation exists among small companies since they tend to be less widely followed by other securities analysts and thus may be more likely to be undervalued by the market. The Fund may invest from time to time a portion of its assets, not to exceed 20% (under normal conditions) at the time of purchase, in companies with larger market capitalizations.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals such as return on equity, earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 25% of its total assets in non U.S. dollar-denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing a maximum of 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small Cap Companies Risk. The Fund will invest in smaller issuers which are more volatile and less liquid than investments in issuers with a market capitalization greater than the market capitalization of companies in the Russell 2000^® Value Index. Small market capitalization issuers are not as diversified in their business activities as issuers with market capitalizations greater than the market capitalization of companies in the Russell 2000^® Value Index and are more susceptible to changes in the business cycle.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 175%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners Small Cap Value Fund II's Investor Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	29.32% (quarter ended June 30, 2009)
Worst Quarter:	(26.42)% (quarter ended December 31, 2008)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Investor Class Prospectus Boston Partners Small Cap Value Fund II		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INVESTOR		3.90%	14.28%	8.09%
INVESTOR After Taxes on Distributions	[1]	3.36%	14.09%	6.70%
INVESTOR After Taxes on Distributions and Sale of Fund Shares		2.47%	11.44%	6.37%
INVESTOR Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)		4.22%	14.26%	6.89%

[1] The Fund's investment adviser, Robeco Investment Management, Inc. (the "Adviser"), has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 1.35% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 1.35%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time during the three years from May 28, 2014 to May 28, 2017 the Fund's Advisory Agreement with the Adviser is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.35%, the Adviser is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by the Adviser to the Fund during such three-year period.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

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Investor Class Prospectus | Boston Partners All-Cap Value Fund | INVESTOR

Boston Partners All-Cap Value Fund

Investment Objective

The Fund seeks to provide long-term growth of capital primarily through investment in equity securities.

Current income is a secondary objective.

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy and hold Investor Class shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Investor Class Prospectus Boston Partners All-Cap Value Fund INVESTOR
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load)	none
Maximum sales charge (load) imposed on reinvested dividends	none
Redemption fee (as a percentage of amount redeemed if applicable)	none
Exchange fee (as a percentage of amount exchanged on shares held for less than 60 days, if applicable)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Investor Class Prospectus Boston Partners All-Cap Value Fund INVESTOR
Management fees		0.80%
Distribution and servicing (12b-1) fees		0.25%
Other expenses		0.14%
Total annual Fund operating expenses		1.19%
Less Fee waivers and expense reimbursements	[1]	(0.24%)
Net expenses		0.95%

Example

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and that you sell all of your shares at the end of the period. The Example also assumes that your investment has a 5% return each year and that the operating expenses of the Fund remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Investor Class Prospectus Boston Partners All-Cap Value Fund INVESTOR	97	354	631	1,422

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Total Annual Fund Operating Expenses or in the Example, affect the Fund's performance. During the fiscal year ended August 31, 2014, the portfolio turnover rate for the Fund was 26% of the average value of its portfolio.

Summary of Principal Investment Strategies

The Fund pursues its objective by investing, under normal circumstances, at least 80% of its net assets (including borrowings for investment purposes) in a diversified portfolio consisting primarily of equity securities, such as common stocks of issuers across the capitalization spectrum and identified by the Adviser as having value characteristics.

The Adviser will sell a stock when it no longer meets one or more investment criteria, either through obtaining target value or due to an adverse change in fundamentals or business momentum. Each holding has a target valuation established at purchase, which the Adviser constantly monitors and adjusts as appropriate.

The Adviser examines various factors in determining the value characteristics of such issuers including price to book value ratios and price to earnings ratios. These value characteristics are examined in the context of the issuer's operating and financial fundamentals, such as return on equity and earnings growth and cash flow. The Adviser selects securities for the Fund based on a continuous study of trends in industries and companies, earnings power and growth and other investment criteria.

The Fund may also invest up to 20% of its total assets in non U.S. dollar denominated securities.

The Fund may invest up to 15% of its net assets in illiquid securities, including securities that are illiquid by virtue of the absence of a readily available market or legal or contractual restrictions on resale.

The Fund may participate as a purchaser in initial public offerings of securities ("IPO"). An IPO is a company's first offering of stock to the public.

The Fund may invest up to 10% of its net assets in securities that can be converted into common stock, such as certain debt securities and preferred stock.

The Fund may hedge overall portfolio exposure up to 40% of its net assets through the purchase and sale of index and individual put and call options.

In general, the Fund's investments are broadly diversified over a number of industries and, as a matter of policy, the Fund is limited to investing less than 25% of its total assets in any one industry.

While the Adviser intends to fully invest the Fund's assets at all times in accordance with the above-mentioned policies, the Fund reserves the right to hold up to 100% of its assets, as a temporary defensive measure, in cash and eligible U.S. dollar-denominated money market instruments. The Adviser will determine when market conditions warrant temporary defensive measures.

Summary of Principal Risks

•  Management Risk. The Fund is subject to the risk of poor stock selection. In other words, the individual stocks in the Fund may not perform as well as expected, and/or the Fund's portfolio management practices do not work to achieve their desired result.

•  Market Risk. The net asset value ("NAV") of the Fund will change with changes in the market value of its portfolio positions. Investors may lose money. Although the Fund will invest in stocks the Adviser believes to be undervalued, there is no guarantee that the prices of these stocks will not move even lower.

•  Foreign Securities Risk. International investing is subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, and differences in taxation, auditing and other financial practices.

•  Small/Mid-Cap Companies Risk. Investing in securities of companies with micro, small or mid-sized capitalizations tends to be riskier than investing in securities of companies with large capitalizations. Securities of companies with micro, small and mid-sized capitalizations tend to be more volatile than those of large cap companies and, on occasion, may fluctuate in the opposite direction of large cap company securities or the broader stock market averages.

The small capitalization equity securities in which the Fund invests may be traded only in the over-the- counter market or on a regional securities exchange, may be listed only in the quotation service commonly known as the "pink sheets," and may not be traded every day or in the volume typical of trading on a national securities exchange. These securities may also be subject to wide fluctuations in market value. The trading market for any given small capitalization equity security may be sufficiently small as to make it difficult for the Fund to dispose of a substantial block of such securities. The sale by the Fund of portfolio securities to meet redemptions may require the Fund to sell its small capitalization securities at a discount from market prices or during periods when, in the Adviser's judgment, such sale is not desirable. Moreover, the lack of an efficient market for these securities may make them difficult to value.

•  Convertible Securities Risk. Securities that can be converted into common stock, such as certain securities and preferred stock, are subject to the usual risks associated with fixed income investments, such as interest rate risk and credit risk. In addition, because they react to changes in the value of the equity securities into which they will convert, convertible securities are also subject to the risks associated with equity securities.

•  Portfolio Turnover Risk. If the Fund frequently trades its portfolio securities, the Fund will incur higher brokerage commissions and transaction costs, which could lower the Fund's performance. In addition to lower performance, high portfolio turnover could result in taxable capital gains. The annual portfolio turnover rate for the Fund is not expected to exceed 125%; however, it may be higher if the Adviser believes it will improve the Fund's performance.

•  Options Risk. An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a "call") or sell (a "put") an asset in the near future at an agreed upon price prior to the expiration date of the option. The Fund may "cover" a call option by owning the security underlying the option or through other means. The value of options can be highly volatile, and their use can result in loss if the Adviser is incorrect in its expectation of price fluctuations.

•  Illiquid Securities Risk. Investing in illiquid securities is subject to certain risks, such as limitations on resale and uncertainty in determining valuation. Limitations on resale may adversely affect the marketability of portfolio securities and the Fund might be unable to dispose of restricted or other illiquid securities promptly or at reasonable prices and might thereby experience difficulty satisfying redemptions within seven days. The Fund might, in order to dispose of restricted securities, have to register securities resulting in additional expense and delay. Adverse market conditions could impede such a public offering of such securities.

•  IPO Risk. IPO risk is the risk that the market value of IPO shares will fluctuate considerably due to certain factors, such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. When the Fund's asset base is small, a significant portion of the Fund's performance could be attributable to investments in IPOs, because such investments would have a magnified impact on the Fund. As the Fund's assets grow, the effect of the Fund's investments in IPOs on the Fund's performance probably will decline, which could reduce the Fund's performance. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of the Fund's portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. In addition, the Adviser cannot guarantee continued access to IPOs.

Performance Information

The bar chart and table below illustrate the long-term performance of the Boston Partners All-Cap Value Fund's Investor Class. The bar chart below shows you how the Fund's performance has varied year by year and provides some indication of the risks of investing in the Fund. The bar chart assumes reinvestment of dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. Performance reflects fee waivers in effect. If fee waivers were not in place, the Fund's performance would be reduced. Updated performance information is available at www.boston-partners.com or 1-888-261-4073.

Total Returns for the Calendar Years Ended December 31

Best and Worst Quarterly Performance (for the periods reflected in the chart above):

Best Quarter:	18.56% (quarter ended June 30, 2009)
Worst Quarter:	(17.62)% (quarter ended September 30, 2011)

Average Annual Total Returns

Average Annual Total Returns for the Periods Ended December 31, 2014

The table below compares the average annual total returns for the Fund's Investor Class both before and after taxes for the past calendar year, past five calendar years and past ten calendar years to the average annual total returns of a broad-based securities market index for the same periods.

Average Annual Returns Investor Class Prospectus Boston Partners All-Cap Value Fund		Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years
INVESTOR		11.98%	14.90%	9.46%
INVESTOR After Taxes on Distributions	[1]	10.30%	13.71%	8.28%
INVESTOR After Taxes on Distributions and Sale of Fund Shares		7.35%	11.61%	7.37%
INVESTOR Russell 3000® Value Index (reflects no deduction for fees, expenses or taxes)		12.70%	15.34%	7.26%

[1] The Fund's Adviser has contractually agreed to waive all or a portion of its advisory fee and/or reimburse expenses in an aggregate amount equal to the amount by which the Total annual Fund operating expenses (excluding certain items discussed below) for the Fund's Investor Class shares exceeds 0.95% of the average daily net assets attributable to the Fund's Investor Class shares. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total annual Fund operating expenses to exceed 0.95%: acquired fund fees and expenses, short sale dividend expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until January 26, 2016 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. The Adviser may not recoup any of its waived investment advisory fees.

[1] After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.