Robeco Boston Partners Long/Short Research Fund (First Prospectus Summary) | Robeco Boston Partners Long/Short Research Fund

SUMMARY SECTION

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	Robeco 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		Robeco Boston Partners Long/Short Research Fund Institutional Class
Management fees		1.25%
Distribution (12b-1) fees		none
Dividend expense on short sales		0.45%
Interest expense on borrowings		0.51%
Other operating expenses		1.99%
Total other expenses		2.95%
Total annual Fund operating expenses		4.20%
Fees forgone and expense reimbursements	[1]	(1.74%)
Net expenses (includes dividend expenses on short sales and interest expense on borrowings)		2.46%

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 $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years	Expense Example, With Redemption, 5 Years	Expense Example, With Redemption, 10 Years
Robeco Boston Partners Long/Short Research Fund Institutional Class	249	1,117	2,000	4,268

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, 2011, the portfolio

turnover rate for the Fund was 61%.

Summary of Principal Investment Strategies

The Fund will use a hedged strategy. The Fund actively invests in long positions

in stocks identified by Robeco as undervalued and takes short positions in

stocks that Robeco 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 will invest, 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, mortgage-backed securities, 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

Robeco. Robeco 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.



Robeco 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 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. Robeco selects stocks on the basis of three criteria: value,

fundamental business strength and momentum. Robeco 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. Robeco 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 will seek 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 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 Robeco 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. Robeco will determine

when market conditions warrant temporary defensive measures.

Summary of Principal Risks

o 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 Robeco believes to

be undervalued, there is no guarantee that the price of these stocks will not

move even lower.



o 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.



o 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.



o 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.



o Management Risk. The Fund is subject to the risk of poor stock selection.

Robeco 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 Robeco

will manage both a long and a short portfolio, there is the risk that Robeco may

make more poor investment decisions than an adviser of a typical stock mutual

fund with only a long portfolio.



o 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.



o 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.



o 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 Robeco's judgment, such sale is not

desirable. Moreover, the lack of an efficient market for these securities may

make them difficult to value.



o 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.



o 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 Robeco believes it will improve the Fund's

performance.



o 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.



o 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.



o 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.



o 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.



o 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

No performance information is available for the Fund because it has not been in

operation for a full calendar year. The performance information, when available,

will provide some indication of the risks of investing in the Fund. The Fund

intends to evaluate its performance as compared to that of the Standard & Poor's

500 Index. Updated performance information is available at www.robecoinvest.com

or 1-888-261-4073.

[1] The Fund's investment adviser, Robeco Investment Management, Inc. ("Robeco"), 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 December 31, 2012 and may not be terminated without Board approval. If at any time during the first three years the Fund's Advisory Agreement with Robeco is in effect, the Fund's Total annual Fund operating expenses for that year are less than 1.50%, Robeco is entitled to reimbursement by the Fund of the advisory fees forgone and other payments remitted by Robeco to the Fund during such three-year period.