N-CSR

Item 1: Report to Shareholders

 Mid-Cap Growth Fund December 31, 2007 

The views and opinions in this report were current as of December 31, 2007. They are not guarantees of performance or investment results and should not be taken as investment advice. Investment decisions reflect a variety of factors, and the managers reserve the right to change their views about individual stocks, sectors, and the markets at any time. As a result, the views expressed should not be relied upon as a forecast of the fund’s future investment intent. The report is certified under the Sarbanes-Oxley Act, which requires mutual funds and other public companies to affirm that, to the best of their knowledge, the information in their financial reports is fairly and accurately stated in all material respects.

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Manager’s Letter

Fellow Shareholders

In our midyear report, we noted that Wall Street’s mood had remained somewhat ebullient, even though conditions on Main Street were more subdued. Times have changed. Over the past six months, Wall Street’s mood has ranged from panicked, to hopeful, to depressed as the credit markets experienced their most significant turmoil in years. If there was a silver lining, it was that conditions in the financial markets realigned with those in the real economy, possibly laying the groundwork for better times ahead. Thanks in part to its growth focus, your fund was able to record a modest return in the past six months that added to our more substantial gain earlier in the year.

The Mid-Cap Growth Fund returned 2.18% during the past six months and 17.65% for the 12-month period ended December 31, 2007. (Returns for Advisor and R Class shares were lower due to their different fee structure.) The fund handily outpaced both the S&P MidCap 400 and Russell Midcap Growth Indexes over both periods. Despite the especially strong performance of the Lipper Mid-Cap Growth Funds Index, the fund remained favorably ranked relative to its peers for both the one-year and longer time periods. (Based on cumulative total return, Lipper ranked the Mid-Cap Growth Fund 243 out of 601, 173 out of 487, 92 out of 404, and 17 out of 170 funds in the category for the 1-, 3-, 5-, and 10-year periods ended December 31, 2007. Results will vary for other time periods. Past performance cannot guarantee future results.)

HIGHLIGHTS

• Wall Street’s mood changed dramatically over the past six months due to turmoil in the credit markets.

• The fund handily outpaced the S&P MidCap 400 and Russell Midcap Growth Indexes for both the last six months and the year as a whole.

• Strong performance from our information technology holdings helped the fund while telecommunications services holdings detracted.

• The economy faces significant challenges in coming months, but we are hopeful that the cleansing of recent financial excesses will set the stage for better times ahead, particularly for growth companies.

MARKET ENVIRONMENT

History will likely show that the U.S. economy reached a cyclical peak sometime in 2007. While the official data on gross domestic product indicate that the economy grew robustly through the third quarter of 2007, many other signs suggested that growth was decelerating sharply through the second half of the year. By the end of 2007, some economists were arguing that the U.S. had entered into a recession, while optimists were hoping that the economy might enjoy a “soft landing”—or a period of subpar but positive growth.

While time will tell which camp was correct, the economy certainly appeared to be following a textbook slowdown. Unlike the recent investment-led recession of 2000-2001, the current slowdown followed a more common pattern—last seen in 1990-1991—and was led by worsening consumer conditions. Particularly hard pressed were lower-income individuals, who saw family budgets seriously pinched by $3.00 gasoline and higher home heating bills. The holiday shopping season proved a poor one for retailers, and disappointing results for high-end merchants suggested even affluent consumers were pulling back.

As in 1990, a major stress facing consumers was the declining housing market. Hopes that the housing slump would hit a bottom in 2007 proved unfounded. Home values continued to decline as inventories rose, with the deterioration most dramatic in struggling economic areas such as Detroit and formerly hot markets such as Florida. Abandoned properties began to appear on cul-de-sacs around the nation as the foreclosure rate rose dramatically, particularly on homes financed with subprime loans. A few million more adjustable rate loans are scheduled to reset to higher payments in the next two years.

While the healthy job market provided some relief to consumers, labor market conditions began to wane as 2007 progressed. The unemployment rate crept up from around 4.5% at the start of the year to 5.0% in December—hardly an alarming level, but evidence of a deterioration in conditions. Wage gains also struggled to keep up with inflation. The U.S. consumer price index rose 4.1% in 2007, an acceleration from the 2.5% rate in 2006. This trend bears watching.

Every period of economic history has its own characteristics, of course, and the storm that hit financial markets was one of the most remarkable episodes of the past year. Thanks to accommodating central banks, financial innovation, the concentration of capital overseas, and a long economic expansion that lulled investors’ perception of risk, financial leverage has increased dramatically over the past several years. Hedge funds and private-equity groups became like China Clippers, their “sails” of easy and cheap credit fully extended to take advantage of the winds of the global economy. A single dollar of assets wagered on rising oil prices, for example, could have the effect of several if magnified through the use of esoteric derivatives or bank financing for the takeover of a public company.

This proved a marvelously profitable strategy as long as those winds were blowing in a favorable direction, but the masts began to snap when conditions deteriorated. Significant distress emerged in the secondary market for subprime mortgage loans. As subprime defaults rose, buyers of bundled subprime mortgage securities discovered that their holdings were worth far less than their computer models had indicated. Banks and other institutions took dramatic writedowns on their balance sheets, which led, in turn, to a decline in liquidity, and stress in other types of financial vehicles unfamiliar to most outsiders (CDOs, SIVs). By the end of the year, a startling number of vessels were floundering—Citigroup, Bear Stearns, and Countrywide Financial to name only a few. The decline in the takeover market was also dramatic, as private equity suddenly found that their sources of credit had disappeared.

The worrisome economic signals and the spectacle unfolding in the financial markets were enough to encourage a sharp shift in monetary policy. The Federal Reserve intervened both by guiding official short-term interest rates lower for the first time in over four years, and by injecting liquidity into the corporate credit markets. Anxious investors bid stocks higher at news of Fed intervention, hoping that the central bank would cause the storm clouds to part. Whether the Fed could—or even should—lower rates quickly remained open to debate. Certainly, the Fed risked debasing the currency, especially given the worrisome inflation signals that emerged as the year wound down.

Thanks in large part to the relief provided by the Fed, 2007 will go down in the market record books as a fairly unremarkable year despite the underlying turmoil. Investors focused their buying on two types of businesses: those perceived to have higher growth potential and those with extensive operations overseas. The broad S&P 500 Index managed a modest gain, while growth stocks outpaced value shares and large- and mid-caps outpaced small-caps. Within the S&P 400 Index of mid-cap shares, energy, materials, and health care stocks fared well overall, while consumer discretionary shares and financials stocks lagged badly.

PORTFOLIO REVIEW

Our fund’s positive return over the past six months was due largely to good results from our energy and information technology holdings; materials, a minor part of the portfolio, also provided a small contribution. Record-high oil prices and continued strong demand for coal drove our results in the energy sector. Coal producer CONSOL Energy and equipment and services firms FMC Technologies and Smith International were particularly strong. (Please see the portfolio of investments for a complete list of holdings and the amount each represents in the portfolio.)

First Solar and Sunpower, although classified as technology firms, also benefited from the world’s continued thirst for new energy sources. These alternative energy stocks delivered extremely strong returns that, in fact, showed signs of speculative fervor. We have significantly reduced our holdings in the two firms as valuations have become stretched. As we noted in our last report, we have begun to assemble a “farm team” of alternative energy stocks and believe we will be offered additional entry points into the industry over time.

Our results elsewhere in the technology sector were less uniformly positive, but our winners were able to compensate for several disappointments. FLIR Systems, a leading purveyor of thermal and infrared technology spanning commercial and defense applications, enjoyed good growth in both markets. Juniper Networks, a leading provider of computer network equipment, benefited from a robust product cycle. However, our semiconductor holdings fared poorly due to worries about the firms’ end markets. Teradyne, Intersil, and Marvell Technology Group were all notable detractors.

Our consumer-oriented technology holdings benefited as electronic games and devices proved to be one of the last areas in which consumers cut back. Anyone who has ever owned a stereo is familiar with the name of Dolby Laboratories, which we have owned since its initial public offering (IPO). The company continued to draw income from the use of its technologies in the consumer electronics that are proliferating in our homes. Likewise, electronic map provider NAVTEQ capitalized on significant demand for its software used in GPS systems. According to industry analysts, sales of portable navigation devices—one of this year’s must-have holiday gifts—are roughly doubling each year. Harman International, a leading manufacturer of in-built GPS systems in higher-end cars, was left far behind in the trend: Shares plummeted as KKR and Goldman Sachs Group’s private-equity unit pulled out of their purchase of the company, coinciding with Harman’s announcement of an earnings shortfall.

Two strong consumer performers were Amazon.com and Chipotle Mexican Grill. Both companies have benefited from their unique approach to their businesses, whether in the use of technology in retailing or a focus on healthy eating. We have begun to trim our holdings in Amazon as its potential has become better reflected in its valuation and as it has moved into the large-cap sector.

Most of our holdings in the consumer sector were unable to escape the downdraft of slowing sales. Our strategy in the sector, which has often been the source of good returns for us in the past, has been to focus on so-called “category killers,” or firms that dominate their markets. This approach has helped our results significantly over the years but even leading companies felt the sting of the recent weakened consumer environment. PetSmart was a notable detractor as it failed to meet profit expectations. CarMax, which we believe is uniquely positioned to gain share in the massive used auto market, struggled with slowing car sales and tightening consumer financing conditions. Bed Bath & Beyond took blows as rival Linens ’n Things slashed prices while it failed to avoid bankruptcy.

Telecommunications services holdings were a source of weakness for the fund. Our poor results here stemmed largely from our twin holdings in MetroPCS Communications and Leap Wireless. Both cater to lower-end consumers, who have been inordinately hurt by the economic deterioration.

No long-term portfolio is recession proof, but we feel our fund is well positioned for the slowing economic environment. We have always paid particular attention to corporate balance sheets, in good times and bad. In the last couple of years, we have generally avoided credit-sensitive companies, as we believed investors were not being adequately compensated for increasing risks. Our performance benefited from our conservative bent in 2007, though the reverse could be true if speculative juices begin to flow again in 2008. In other areas, we have trimmed holdings in which we have made good gains but are now seeing somewhat extended valuations. Most notably, we are reducing our energy exposure after a period of strong performance, as we believe the slowing global economy is likely to mute energy demand.

INVESTMENT STRATEGY AND OUTLOOK

Events have shown that the choppy waters we described in our letter last summer were only a hint of the storm over the horizon. As we write, the broad market is perilously close to bear territory, having surrendered nearly 20% since its highs last summer. Credit markets remain in a state of turmoil, and most observers expect more banks and institutional investors to come forward with losses suffered in the subprime debacle.

Political leaders have called for economic stimulus to prevent a recession—or at least help the economy bounce back quickly if it has already entered one. In perhaps the most conclusive sign of troubled times, the Federal Reserve has, to date, lowered the federal funds rate by 175 basis points (1.75%) in slightly more than four months.

Storms of this size always leave their mark on the landscape. Indeed, we have the sense that the current turmoil may mark the end of the easy money economy, which began in earnest in late 2001, when the Fed began to guide rates aggressively lower in order to restore confidence following 9/11. The easy money era itself reflected the imprint of previous times, having been built on the ruins of the dot-com boom of the late 1990s. Record-low interest rates—the Fed guided the federal funds rate as low as 1% in June 2003—had been intended to keep businesses borrowing and consumers buying following the severe contraction in business investment that accompanied the brief recession of 2000-2001. While business spending improved marginally and consumer demand remained healthy, few could have foreseen the other channels into which the gusher of money would flow, whether those were inflated Florida condo prices or the bank accounts of Wall Street moguls.

While the shape of the coming era will probably bring its own surprises, it seems clear that businesses and individuals reliant on flows of cheap and easy credit will find conditions much more challenging. Evidence of the credit reversal is already abundant, most distressingly in the foreclosure signs dotting the landscape. Even after months of sharp declines, housing prices remain elevated compared with long-term trends, and the pain in the housing sector appears likely to continue for at least another year. The credit contraction has spread far beyond the housing sector; conditions in consumer credit cards, commercial real estate, and small business loans have all deteriorated in recent months. Credit spreads, or the extra yield demanded on loans to higher-risk borrowers, have increased dramatically since July.

A less sympathetic victim of the changed conditions has been the private-equity buyer. As we have commented in past letters, several of our holdings were acquired by private firms at prices that we felt did not reflect the long-term value of the businesses. Private-equity firms took advantage of cheap debt, the short-term orientation of many investors who evaluated the deals based on recent stock prices rather than long-term business values, and the acquiescence of management teams attracted by the lure of equity participation. With private equity sidelined for the time being, we hope to benefit more fully from our investments as the market gradually recognizes their underlying value. Still, the virtual evaporation of private-equity activity in the fall removed a driver behind the prices of some stocks in the portfolio, temporarily dampening performance.

While banks have been hurt by the credit market turmoil, they may, in fact, be longer-term beneficiaries. Over the last quarter century, banks have had many of their traditional functions disintermediated by a wide variety of financial upstarts; for instance, mortgage brokers have replaced bank officers as distributors of home loans. In the last decade, the credit creation process has been usurped by less-regulated entities through the securitization process, which divorced the origination of credit from the ultimate holder of the loan. It is not particularly surprising that this culminated in the extension of loans to unqualified applicants. Ultimately, the credit markets have seized up and there may be an opportunity for banks to reintermediate, or reconnect, some of this lost business.

As we write, the U.S. monetary and political authorities are engineering significant economic stimulus aimed at softening the blow of an economic downturn. Time will tell whether their actions are warranted. Recessions are unpleasant, and their toll is shared unevenly by those who lose their jobs and lower-paid workers. However, recessions are also capitalism’s cleansing process. They redress imbalances that have built up in good times and punish speculators. The spectacle of the consequences of ignoring risk inoculates the economic participants from repeating similar mistakes, at least for a time.

The Federal Reserve will have a large impact on the economy, of course, although we suspect it may not be the savior that many hope. Indeed, the central bank has assumed an almost mythical role in investors’ eyes in the nearly 30 years since Fed Chairman Paul Volcker slew the beast of double-digit inflation and his successor Alan Greenspan helped usher in the not-too-hot, not-too-cold “Goldilocks economy.” In continuing to cut interest rates aggressively even as price pressures increase, however, the Fed risks unleashing a renewed era of inflationary expectations—a long-term risk to the economy that is far more serious than a recession. As the experience of the early 1980s showed, ridding the economy of inflationary pressures is a difficult and unpleasant task. It is also worth noting that the Fed will face as much difficulty controlling the contraction in credit as it did guiding its expansion.

Despite the short-term challenges that lie ahead, we are mindful that the transformed financial landscape should eventually create winners as well as losers. For example, the withdrawal of private-equity firms from the takeover market has left the hunting ground open for strategic acquirers. We are hopeful that some of the companies in our portfolio will have renewed opportunities to expand through the acquisition of competitors, suppliers, or downstream vendors. Also, as banks take loans back on their balance sheets, they will be forced to do a better job of allocating credit, which should benefit responsibly managed companies. More generally, we are hopeful that a renewed focus on organic growth will favor the companies that have always been the focus of our fund: those that are able to grow by leveraging superior technologies or market positions, not borrowed money.

Respectfully submitted,

Brian W.H. Berghuis
President of the fund and chairman of its Investment Advisory Committee

John F. Wakeman
Executive vice president of the fund

January 22, 2008

The committee chairman has day-to-day responsibility for managing the portfolio and works with committee members in developing and executing the fund’s investment program.

RISKS OF STOCK INVESTING

As with all stock and bond mutual funds, the fund’s share price can fall because of weakness in the stock or bond markets, a particular industry, or specific holdings. The financial markets can decline for many reasons, including adverse political or economic developments, changes in investor psychology, or heavy institutional selling. The prospects for an industry or company may deteriorate because of a variety of factors, including disappointing earnings or changes in the competitive environment. In addition, the investment manager’s assessment of companies held in a fund may prove incorrect, resulting in losses or poor performance even in rising markets. The stocks of mid-cap companies entail greater risk and are usually more volatile than the shares of larger companies. In addition, growth stocks can be volatile for several reasons. Since they usually reinvest a high proportion of earnings in their own businesses, they may lack the dividends usually associated with value stocks that can cushion their decline in a falling market. Also, since investors buy these stocks because of their expected superior earnings growth, earnings disappointments often result in sharp price declines.

GLOSSARY

Lipper indexes: Fund benchmarks that consist of a small number of the largest mutual funds in a particular category as tracked by Lipper Inc.

Russell Midcap Growth Index: An unmanaged index that measures the performance of those Russell Midcap companies with higher price-to-book ratios and higher forecasted growth values.

Russell Midcap Value Index: An unmanaged index that measures the performance of those Russell Midcap companies with lower price-to-book ratios and lower forecasted growth values.

S&P 500 Stock Index: An unmanaged index that tracks the stocks of 500 primarily large-cap U.S. companies.

S&P MidCap 400 Index: An unmanaged index that tracks the stocks of 400 U.S. mid-cap companies.

Performance and Expenses

GROWTH OF $10,000 

This chart shows the value of a hypothetical $10,000 investment in the fund over the past 10 fiscal year periods or since inception (for funds lacking 10-year records). The result is compared with benchmarks, which may include a broad-based market index and a peer group average or index. Market indexes do not include expenses, which are deducted from fund returns as well as mutual fund averages and indexes.

AVERAGE ANNUAL COMPOUND TOTAL RETURN 

This table shows how the fund would have performed each year if its actual (or cumulative) returns had been earned at a constant rate.

FUND EXPENSE EXAMPLE 

As a mutual fund shareholder, you may incur two types of costs: (1) transaction costs, such as redemption fees or sales loads, and (2) ongoing costs, including management fees, distribution and service (12b-1) fees, and other fund expenses. The following example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds. The example is based on an investment of $1,000 invested at the beginning of the most recent six-month period and held for the entire period.

Please note that the fund has three share classes: The original share class (“investor class”) charges no distribution and service (12b-1) fee; Advisor Class shares are offered only through unaffiliated brokers and other financial intermediaries and charge a 0.25% 12b-1 fee; R Class shares are available to retirement plans serviced by intermediaries and charge a 0.50% 12b-1 fee. Each share class is presented separately in the table.

Actual Expenses
The first line of the following table (“Actual”) provides information about actual account values and expenses based on the fund’s actual returns. You may use the information in this line, together with your account balance, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes
The information on the second line of the table (“Hypothetical”) is based on hypothetical account values and expenses derived from the fund’s actual expense ratio and an assumed 5% per year rate of return before expenses (not the fund’s actual return). You may compare the ongoing costs of investing in the fund with other funds by contrasting this 5% hypothetical example and the 5% hypothetical examples that appear in the shareholder reports of the other funds. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period.

Note: T. Rowe Price charges an annual small-account maintenance fee of $10, generally for accounts with less than $2,000 ($500 for UGMA/UTMA). The fee is waived for any investor whose T. Rowe Price mutual fund accounts total $25,000 or more, accounts employing automatic investing, and IRAs and other retirement plan accounts that utilize a prototype plan sponsored by T. Rowe Price (although a separate custodial or administrative fee may apply to such accounts). This fee is not included in the accompanying table. If you are subject to the fee, keep it in mind when you are estimating the ongoing expenses of investing in the fund and when comparing the expenses of this fund with other funds.

You should also be aware that the expenses shown in the table highlight only your ongoing costs and do not reflect any transaction costs, such as redemption fees or sales loads. Therefore, the second line of the table is useful in comparing ongoing costs only and will not help you determine the relative total costs of owning different funds. To the extent a fund charges transaction costs, however, the total cost of owning that fund is higher.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

The accompanying notes are an integral part of these financial statements.

NOTES TO FINANCIAL STATEMENTS 

NOTE 1 - SIGNIFICANT ACCOUNTING POLICIES

T. Rowe Price Mid-Cap Growth Fund, Inc. (the fund), is registered under the Investment Company Act of 1940 (the 1940 Act) as a diversified, open-end management investment company. The fund seeks to provide long-term capital appreciation by investing in mid-cap stocks with potential for above-average earnings growth. The fund has three classes of shares: the Mid-Cap Growth Fund original share class, referred to in this report as the Investor Class, offered since June 30, 1992; the Mid-Cap Growth Fund—Advisor Class (Advisor Class), offered since March 31, 2000; and the Mid-Cap Growth Fund—R Class (R Class), offered since September 30, 2002. Advisor Class shares are sold only through unaffiliated brokers and other unaffiliated financial intermediaries, and R Class shares are available to retirement plans serviced by intermediaries. The Advisor Class and R Class each operate under separate Board-approved Rule 12b-1 plans, pursuant to which each class compensates financial intermediaries for distribution, shareholder servicing, and/or certain administrative services. Each class has exclusive voting rights on matters related solely to that class, separate voting rights on matters that relate to all classes, and, in all other respects, the same rights and obligations as the other classes.

The accompanying financial statements were prepared in accordance with accounting principles generally accepted in the United States of America, which require the use of estimates made by fund management. Fund management believes that estimates and security valuations are appropriate; however, actual results may differ from those estimates, and the security valuations reflected in the financial statements may differ from the value the fund ultimately realizes upon sale of the securities.

Valuation The fund values its investments and computes its net asset value per share at the close of the New York Stock Exchange (NYSE), normally 4 p.m. ET, each day that the NYSE is open for business. Equity securities listed or regularly traded on a securities exchange or in the over-the-counter (OTC) market are valued at the last quoted sale price or, for certain markets, the official closing price at the time the valuations are made, except for OTC Bulletin Board securities, which are valued at the mean of the latest bid and asked prices. A security that is listed or traded on more than one exchange is valued at the quotation on the exchange determined to be the primary market for such security. Listed securities not traded on a particular day are valued at the mean of the latest bid and asked prices for domestic securities and the last quoted sale price for international securities.

Investments in mutual funds are valued at the mutual fund’s closing net asset value per share on the day of valuation.

Other investments, including restricted securities, and those for which the above valuation procedures are inappropriate or are deemed not to reflect fair value are stated at fair value as determined in good faith by the T. Rowe Price Valuation Committee, established by the fund’s Board of Directors.

Most foreign markets close before the close of trading on the NYSE. If the fund determines that developments between the close of a foreign market and the close of the NYSE will, in its judgment, materially affect the value of some or all of its portfolio securities, which in turn will affect the fund’s share price, the fund will adjust the previous closing prices to reflect the fair value of the securities as of the close of the NYSE, as determined in good faith by the T. Rowe Price Valuation Committee, established by the fund’s Board of Directors. A fund may also fair value securities in other situations, such as when a particular foreign market is closed but the fund is open. In deciding whether to make fair value adjustments, the fund reviews a variety of factors, including developments in foreign markets, the performance of U.S. securities markets, and the performance of instruments trading in U.S. markets that represent foreign securities and baskets of foreign securities. The fund uses outside pricing services to provide it with closing market prices and information used for adjusting those prices. The fund cannot predict when and how often it will use closing prices and when it will adjust those prices to reflect fair value. As a means of evaluating its fair value process, the fund routinely compares closing market prices, the next day’s opening prices in the same markets, and adjusted prices.

Currency Translation Assets, including investments, and liabilities denominated in foreign currencies are translated into U.S. dollar values each day at the prevailing exchange rate, using the mean of the bid and asked prices of such currencies against U.S. dollars as quoted by a major bank. Purchases and sales of securities, income, and expenses are translated into U.S. dollars at the prevailing exchange rate on the date of the transaction. The effect of changes in foreign currency exchange rates on realized and unrealized security gains and losses is reflected as a component of security gains and losses.

Class Accounting The Advisor Class and R Class each pay distribution, shareholder servicing, and/or certain administrative expenses in the form of Rule 12b-1 fees, in an amount not exceeding 0.25% and 0.50%, respectively, of the class’s average daily net assets. Shareholder servicing, prospectus, and shareholder report expenses incurred by each class are charged directly to the class to which they relate. Expenses common to all classes, investment income, and realized and unrealized gains and losses are allocated to the classes based upon the relative daily net assets of each class.

Rebates and Credits Subject to best execution, the fund may direct certain security trades to brokers who have agreed to rebate a portion of the related brokerage commission to the fund in cash. Commission rebates are reflected as realized gain on securities in the accompanying financial statements and totaled $357,000 for the year ended December 31, 2007. Additionally, the fund earns credits on temporarily uninvested cash balances at the custodian that reduce the fund’s custody charges. Custody expense in the accompanying financial statements is presented before reduction for credits, which are reflected as expenses paid indirectly.

In-Kind Redemptions In accordance with guidelines described in the fund’s prospectus, the fund may distribute portfolio securities rather than cash as payment for a redemption of fund shares (in-kind redemption). For financial reporting purposes, the fund recognizes a gain on in-kind redemptions to the extent the value of the distributed securities on the date of redemption exceeds the cost of those securities. Gains and losses realized on in-kind redemptions are not recognized for tax purposes and are reclassified from undistributed realized gain (loss) to paid-in capital. During the year ended December 31, 2007, the fund realized $41,738,000 of net gain on $83,115,000 of in-kind redemptions.

Investment Transactions, Investment Income, and Distributions Income and expenses are recorded on the accrual basis. Dividends received from mutual fund investments are reflected as dividend income; capital gain distributions are reflected as realized gain/loss. Dividend income and capital gain distributions are recorded on the ex-dividend date. Income tax-related interest and penalties, if incurred, would be recorded as income tax expense. Investment transactions are accounted for on the trade date. Realized gains and losses are reported on the identified cost basis. Distributions to shareholders are recorded on the ex-dividend date. Income distributions are declared and paid by each class on an annual basis. Capital gain distributions, if any, are declared and paid by the fund, typically on an annual basis.

New Accounting Pronouncements Effective June 29, 2007, the fund adopted Financial Accounting Standards Board (FASB) Interpretation No. 48 (FIN 48), Accounting for Uncertainty in Income Taxes, a clarification of FASB Statement No. 109, Accounting for Income Taxes. FIN 48 establishes financial accounting and disclosure requirements for recognition and measurement of tax positions taken or expected to be taken on an income tax return. The adoption of FIN 48 had no impact on the fund’s net assets or results of operations.

In September 2006, the FASB released the Statement of Financial Accounting Standard No. 157 (FAS 157), Fair Value Measurements. FAS 157 clarifies the definition of fair value and establishes the framework for measuring fair value, as well as proper disclosure of this methodology in the financial statements. It will be effective for the fund’s fiscal year beginning January 1, 2008. Management is evaluating the effects of FAS 157; however, it is not expected to have a material impact on the fund’s net assets or results of operations.

NOTE 2 - INVESTMENT TRANSACTIONS

Consistent with its investment objective, the fund engages in the following practices to manage exposure to certain risks or to enhance performance. The investment objective, policies, program, and risk factors of the fund are described more fully in the fund’s prospectus and Statement of Additional Information.

Restricted Securities The fund may invest in securities that are subject to legal or contractual restrictions on resale. Prompt sale of such securities at an acceptable price may be difficult due to substantial delays and additional costs related to their restrictions.

Securities Lending The fund lends its securities to approved brokers to earn additional income. It receives as collateral cash and U.S. government securities valued at 102% to 105% of the value of the securities on loan. Cash collateral is invested in a money market pooled trust managed by the fund’s lending agent in accordance with investment guidelines approved by fund management. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities, as determined at the close of fund business each day; any additional collateral required due to changes in security values is delivered to the fund the next business day. Although risk is mitigated by the collateral, the fund could experience a delay in recovering its securities and a possible loss of income or value if the borrower fails to return the securities. Securities lending revenue recognized by the fund consists of earnings on invested collateral and borrowing fees, net of any rebates to the borrower and compensation to the lending agent. At December 31, 2007, there were no securities on loan.

Other Purchases and sales of portfolio securities, other than short-term securities, aggregated $5,704,724,000 and $6,377,785,000, respectively, for the year ended December 31, 2007.

NOTE 3 - FEDERAL INCOME TAXES

No provision for federal income taxes is required since the fund intends to continue to qualify as a regulated investment company under Subchapter M of the Internal Revenue Code and distribute to shareholders all of its taxable income and gains. Federal income tax regulations differ from generally accepted accounting principles; therefore, distributions determined in accordance with tax regulations may differ significantly in amount or character from net investment income and realized gains for financial reporting purposes. Financial reporting records are adjusted for permanent book/tax differences to reflect tax character. Financial records are not adjusted for temporary differences.

Distributions during the year ended December 31, 2007, were characterized as follows for tax purposes:

At December 31, 2007, the tax-basis components of net assets were as follows:

For the year ended December 31, 2007, the fund recorded the following permanent reclassifications to reflect tax character. Reclassifications to paid-in capital relate primarily to redemptions in kind and a tax practice that treats a portion of the proceeds from each redemption of capital shares as a distribution of taxable net investment income and/or realized capital gain. Reclassifications between income and gain relate primarily to per share rounding of distributions. Results of operations and net assets were not affected by these reclassifications.

At December 31, 2007, the cost of investments for federal income tax purposes was $12,893,804,000.

NOTE 4 - ACQUISITION

On June 19, 2006, the fund acquired substantially all of the assets of the Preferred Mid-Cap Growth Fund (the acquired fund), pursuant to the Agreement and Plan of Reorganization dated February 15, 2006, and approved by shareholders of the acquired fund on June 9, 2006. The acquisition was accomplished by a tax-free exchange of 317,307 shares of the fund (with a value of $17,008,000) for all 1,615,268 shares of the acquired fund outstanding on June 16, 2006 with the same value. The net assets of the acquired fund at that date included $995,000 of unrealized depreciation. Net assets of the acquired fund were combined with those of the fund, resulting in aggregate net assets of $14,974,367,000 immediately after the acquisition.

NOTE 5 - RELATED PARTY TRANSACTIONS

The fund is managed by T. Rowe Price Associates, Inc. (the manager or Price Associates), a wholly owned subsidiary of T. Rowe Price Group, Inc. The investment management agreement between the fund and the manager provides for an annual investment management fee, which is computed daily and paid monthly. The fee consists of an individual fund fee and a group fee. The individual fund fee is equal to 0.35% of the fund’s average daily net assets up to $15 billion and 0.30% of the fund’s average daily net assets in excess of $15 billion. The group fee rate is calculated based on the combined net assets of certain mutual funds sponsored by Price Associates (the group) applied to a graduated fee schedule, with rates ranging from 0.48% for the first $1 billion of assets to 0.285% for assets in excess of $220 billion. The fund’s group fee is determined by applying the group fee rate to the fund’s average daily net assets. At December 31, 2007, the effective annual group fee r ate was 0.30%.

In addition, the fund has entered into service agreements with Price Associates and two wholly owned subsidiaries of Price Associates (collectively, Price). Price Associates computes the daily share prices and provides certain other administrative services to the fund. T. Rowe Price Services, Inc., provides shareholder and administrative services in its capacity as the fund’s transfer and dividend disbursing agent. T. Rowe Price Retirement Plan Services, Inc., provides subaccounting and recordkeeping services for certain retirement accounts invested in the Investor Class and R Class. For the year ended December 31, 2007, expenses incurred pursuant to these service agreements were $126,000 for Price Associates, $3,254,000 for T. Rowe Price Services, Inc., and $7,413,000 for T. Rowe Price Retirement Plan Services, Inc. The total amount payable at period-end pursuant to these service agreements is reflected as Due to Affiliates in the accompanying financial statements.

Additionally, the fund is one of several mutual funds in which certain college savings plans managed by Price Associates may invest. As approved by the fund’s Board of Directors, shareholder servicing costs associated with each college savings plan are borne by the fund in proportion to the average daily value of its shares owned by the college savings plan. For the year ended December 31, 2007, the fund was charged $191,000 for shareholder servicing costs related to the college savings plans, of which $170,000 was for services provided by Price. The amount payable at period-end pursuant to this agreement is reflected as Due to Affiliates in the accompanying financial statements. At December 31, 2007, approximately 1% of the outstanding shares of the Investor Class were held by college savings plans.

The fund is also one of several mutual funds sponsored by Price Associates (underlying Price funds) in which the T. Rowe Price Retirement Funds (Retirement Funds) may invest. The Retirement Funds do not invest in the underlying Price funds for the purpose of exercising management or control. Pursuant to a special servicing agreement, expenses associated with the operation of the Retirement Funds are borne by each underlying Price fund to the extent of estimated savings to it and in proportion to the average daily value of its shares owned by the Retirement Funds. Expenses allocated under this agreement are reflected as shareholder servicing expense in the accompanying financial statements. For the year ended December 31, 2007, the fund was allocated $2,397,000 of Retirement Funds’ expenses, of which $1,855,000 related to services provided by Price. The amount payable at period-end pursuant to this agreement is reflected as Due to Affiliates in the accompanying financial statements. At December 31, 2007, approximately 8% of the outstanding shares of the Investor Class were held by the Retirement Funds.

The fund may invest in the T. Rowe Price Reserve Investment Fund and the T. Rowe Price Government Reserve Investment Fund (collectively, the T. Rowe Price Reserve Investment Funds), open-end management investment companies managed by Price Associates and affiliates of the fund. The T. Rowe Price Reserve Investment Funds are offered as cash management options to mutual funds, trusts, and other accounts managed by Price Associates and/or its affiliates, and are not available for direct purchase by members of the public. The T. Rowe Price Reserve Investment Funds pay no investment management fees.

As of December 31, 2007, T. Rowe Price Group, Inc., and/or its wholly owned subsidiaries owned 68,622 shares of the Investor Class, representing less than 1% of the fund’s net assets.

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM 

To the Board of Directors and Shareholders of T. Rowe Price Mid-Cap Growth Fund, Inc.

In our opinion, the accompanying statement of assets and liabilities, including the portfolio of investments, and the related statements of operations and of changes in net assets and the financial highlights present fairly, in all material respects, the financial position of T. Rowe Price Mid-Cap Growth Fund, Inc. (the “Fund”) at December 31, 2007, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended and the financial highlights for each of the five years in the period then ended, in conformity with accounting principles generally accepted in the United States of America. These financial statements and financial highlights (hereafter referred to as “financial statements”) are the responsibility of the Fund’s management; our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these financial statements in accordance with the auditing standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits, which included confirmation of securities at December 31, 2007, by correspondence with the custodian and by agreement to the underlying ownership records for T. Rowe Price Government Reserve Investment Fund, provide a reasonable basis for our opinion.

PricewaterhouseCoopers LLP
Baltimore, Maryland
February 12, 2008

TAX INFORMATION (UNAUDITED) FOR THE TAX YEAR ENDED 12/31/07 

We are providing this information as required by the Internal Revenue Code. The amounts shown may differ from those elsewhere in this report because of differences between tax and financial reporting requirements.

The fund’s distributions to shareholders included:

• $269,159,000 from short-term capital gains,

• $1,387,799,000 from long-term capital gains, subject to the 15% rate gains category.

For taxable non-corporate shareholders, $112,702,000 of the fund’s income represents qualified dividend income subject to the 15% rate category.

For corporate shareholders, $104,007,000 of the fund’s income qualifies for the dividends-received deduction.

INFORMATION ON PROXY VOTING POLICIES, PROCEDURES, AND RECORDS 

A description of the policies and procedures used by T. Rowe Price funds and portfolios to determine how to vote proxies relating to portfolio securities is available in each fund’s Statement of Additional Information, which you may request by calling 1-800-225-5132 or by accessing the SEC’s Web site, www.sec.gov. The description of our proxy voting policies and procedures is also available on our Web site, www.troweprice.com. To access it, click on the words “Company Info” at the top of our homepage for individual investors. Then, in the window that appears, click on the “Proxy Voting Policy” navigation button in the top left corner.

Each fund’s most recent annual proxy voting record is available on our Web site and through the SEC’s Web site. To access it through our Web site, follow the directions above, then click on the words “Proxy Voting Record” at the bottom of the Proxy Voting Policy page.

HOW TO OBTAIN QUARTERLY PORTFOLIO HOLDINGS 

The fund files a complete schedule of portfolio holdings with the Securities and Exchange Commission for the first and third quarters of each fiscal year on Form N-Q. The fund’s Form N-Q is available electronically on the SEC’s Web site (www.sec.gov); hard copies may be reviewed and copied at the SEC’s Public Reference Room, 450 Fifth St. N.W., Washington, DC 20549. For more information on the Public Reference Room, call 1-800-SEC-0330.

ABOUT THE FUND’S DIRECTORS AND OFFICERS 

Your fund is governed by a Board of Directors (Board) that meets regularly to review a wide variety of matters affecting the fund, including performance, investment programs, compliance matters, advisory fees and expenses, service providers, and other business affairs. The Board elects the fund’s officers, who are listed in the final table. At least 75% of Board members are independent of T. Rowe Price Associates, Inc. (T. Rowe Price), and T. Rowe Price International, Inc. (T. Rowe Price International); “inside” or “interested” directors are employees or officers of T. Rowe Price. The business address of each director and officer is 100 East Pratt Street, Baltimore, Maryland 21202. The Statement of Additional Information includes additional information about the directors and is available without charge by calling a T. Rowe Price representative at 1-800-225-5132.

Independent Directors
Name
(Year of Birth)	Principal Occupation(s) During Past 5 Years and Directorships of
Year Elected*	Other Public Companies
Jeremiah E. Casey	Director, National Life Insurance (2001 to 2005); Director, The Rouse
(1940)	Company, real estate developers (1990 to 2004); Director, Allfirst
2005	Financial Inc. (previously First Maryland Bancorp) (1983 to 2002)
Anthony W. Deering	Chairman, Exeter Capital, LLC, a private investment firm (2004 to pres-
(1945)	ent); Director, Vornado Real Estate Investment Trust (3/04 to present);
2001	Member, Advisory Board, Deutsche Bank North America (2004 to pres-
	ent); Director, Chairman of the Board, and Chief Executive Officer, The
	Rouse Company, real estate developers (1997 to 2004)
Donald W. Dick, Jr.	Principal, EuroCapital Advisors, LLC, an acquisition and management
(1943)	advisory firm; Chairman, The Haven Group, a custom manufacturer of
1992	modular homes (1/04 to present)
David K. Fagin	Chairman and President, Nye Corporation (6/88 to present); Chairman,
(1938)	Canyon Resources Corp. (8/07 to present); Director, Golden Star
1992	Resources Ltd. (5/92 to present); Director, Pacific Rim Mining Corp.
	(2/02 to present)
Karen N. Horn	Director, Federal National Mortgage Association (9/06 to present);
(1943)	Managing Director and President, Global Private Client Services,
2003	Marsh Inc. (1999 to 2003); Director, Georgia Pacific (5/04 to 12/05),
	Eli Lilly and Company, and Simon Property Group
Theo C. Rodgers	President, A&R Development Corporation (1977 to present)
(1941)
2005

John G. Schreiber	Owner/President, Centaur Capital Partners, Inc., a real estate invest-
(1946)	ment company; Partner, Blackstone Real Estate Advisors, L.P.
2001
*Each independent director oversees 121 T. Rowe Price portfolios and serves until retirement, resignation, or
election of a successor.
Inside Directors
Name
(Year of Birth)
Year Elected*
[Number of T. Rowe Price	Principal Occupation(s) During Past 5 Years and Directorships of
Portfolios Overseen]	Other Public Companies
Edward C. Bernard	Director and Vice President, T. Rowe Price; Vice Chairman of the Board,
(1956)	Director, and Vice President, T. Rowe Price Group, Inc.; Chairman of the
2006	Board, Director, and President, T. Rowe Price Investment Services,
[121]	Inc.; Chairman of the Board and Director, T. Rowe Price Global Asset
	Management Limited, T. Rowe Price Global Investment Services Limited,
	T. Rowe Price Retirement Plan Services, Inc., T. Rowe Price Savings
	Bank, and T. Rowe Price Services, Inc.; Director, T. Rowe Price
	International, Inc.; Chief Executive Officer, Chairman of the Board,
	Director, and President, T. Rowe Price Trust Company; Chairman of
	the Board, all funds
Brian C. Rogers, CFA, CIC	Chief Investment Officer, Director, and Vice President, T. Rowe Price;
(1955)	Chairman of the Board, Chief Investment Officer, Director, and Vice
2006	President, T. Rowe Price Group, Inc.; Vice President, T. Rowe Price
[68]	Trust Company
*Each inside director serves until retirement, resignation, or election of a successor.

Officers
Name (Year of Birth)
Title and Fund(s) Served	Principal Occupation(s)
Kennard W. Allen (1977)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.
P. Robert Bartolo, CPA (1972)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.
Timothy F. Bei, CFA (1973)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.; formerly student, University of
	Virginia (to 2003)
Brian W.H. Berghuis, CFA (1958)	Vice President, T. Rowe Price and T. Rowe Price
President, Mid-Cap Growth Fund	Group, Inc.
Joseph A. Carrier, CPA (1960)	Vice President, T. Rowe Price, T. Rowe Price
Treasurer, Mid-Cap Growth Fund	Group, Inc., T. Rowe Price Investment Services,
	Inc., and T. Rowe Price Trust Company
Henry M. Ellenbogen (1971)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.
Roger L. Fiery III, CPA (1959)	Vice President, T. Rowe Price, T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc., T. Rowe Price International, Inc.,
	and T. Rowe Price Trust Company
John R. Gilner (1961)	Chief Compliance Officer and Vice President,
Chief Compliance Officer, Mid-Cap	T. Rowe Price; Vice President, T. Rowe Price
Growth Fund	Group, Inc., and T. Rowe Price Investment
	Services, Inc.
Gregory S. Golczewski (1966)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Trust Company
Henry H. Hopkins (1942)	Director and Vice President, T. Rowe Price
Vice President, Mid-Cap Growth Fund	Investment Services, Inc., T. Rowe Price Services,
	Inc., and T. Rowe Price Trust Company; Vice
	President, T. Rowe Price, T. Rowe Price Group,
	Inc., T. Rowe Price International, Inc., and
	T. Rowe Price Retirement Plan Services, Inc.
Kris H. Jenner, M.D., D. Phil. (1962)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.

Patricia B. Lippert (1953)	Assistant Vice President, T. Rowe Price and
Secretary, Mid-Cap Growth Fund	T. Rowe Price Investment Services, Inc.
Robert J. Marcotte (1962)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.
Daniel Martino, CFA (1974)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.; formerly Research Analyst and
	Co-portfolio Manager, Taurus Asset Management
	and ONEX (to 2006)
Joseph M. Milano, CFA (1972)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.
Jeffrey Rottinghaus, CPA (1970)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.
Clark R. Shields (1976)	Employee, T. Rowe Price; formerly student,
Vice President, Mid-Cap Growth Fund	Harvard Business School (to 2006); Associate,
	MDT Advisers (to 2004)
Taymour R. Tamaddon, CFA (1976)	Vice President, T. Rowe Price and T. Rowe Price
Vice President, Mid-Cap Growth Fund	Group, Inc.; formerly intern, T. Rowe Price
	(to 2004)
John F. Wakeman (1962)	Vice President, T. Rowe Price and T. Rowe Price
Executive Vice President, Mid-Cap Growth Fund	Group, Inc.
Julie L. Waples (1970)	Vice President, T. Rowe Price
Vice President, Mid-Cap Growth Fund
Unless otherwise noted, officers have been employees of T. Rowe Price or T. Rowe Price International for at least
five years.

Item 2. Code of Ethics.

The registrant has adopted a code of ethics, as defined in Item 2 of Form N-CSR, applicable to its principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. A copy of this code of ethics is filed as an exhibit to this Form N-CSR. No substantive amendments were approved or waivers were granted to this code of ethics during the period covered by this report.

Item 3. Audit Committee Financial Expert.

The registrant’s Board of Directors/Trustees has determined that Ms. Karen N. Horn qualifies as an audit committee financial expert, as defined in Item 3 of Form N-CSR. Ms. Horn is considered independent for purposes of Item 3 of Form N-CSR.

Item 4. Principal Accountant Fees and Services.

(a) – (d) Aggregate fees billed to the registrant for the last two fiscal years for professional services rendered by the registrant’s principal accountant were as follows:

Audit fees include amounts related to the audit of the registrant’s annual financial statements and services normally provided by the accountant in connection with statutory and regulatory filings. Audit-related fees include amounts reasonably related to the performance of the audit of the registrant’s financial statements and specifically include the issuance of a report on internal controls and, if applicable, agreed-upon procedures related to fund acquisitions. Tax fees include amounts related to services for tax compliance, tax planning, and tax advice. The nature of these services specifically includes the review of distribution calculations and the preparation of Federal, state, and excise tax returns. All other fees include the registrant’s pro-rata share of amounts for agreed-upon procedures in conjunction with service contract approvals by the registrant’s Board of Directors/Trustees.

(e)(1) The registrant’s audit committee has adopted a policy whereby audit and non-audit services performed by the registrant’s principal accountant for the registrant, its investment adviser, and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant require pre-approval in advance at regularly scheduled audit committee meetings. If such a service is required between regularly scheduled audit committee meetings, pre-approval may be authorized by one audit committee member with ratification at the next scheduled audit committee meeting. Waiver of pre-approval for audit or non-audit services requiring fees of a de minimis amount is not permitted.

    (2) No services included in (b) – (d) above were approved pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

(f) Less than 50 percent of the hours expended on the principal accountant’s engagement to audit the registrant’s financial statements for the most recent fiscal year were attributed to work performed by persons other than the principal accountant’s full-time, permanent employees.

(g) The aggregate fees billed for the most recent fiscal year and the preceding fiscal year by the registrant’s principal accountant for non-audit services rendered to the registrant, its investment adviser, and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant were $1,486,000 and $1,401,000, respectively, and were less than the aggregate fees billed for those same periods by the registrant’s principal accountant for audit services rendered to the T. Rowe Price Funds.

(h) All non-audit services rendered in (g) above were pre-approved by the registrant’s audit committee. Accordingly, these services were considered by the registrant’s audit committee in maintaining the principal accountant’s independence.

Item 5. Audit Committee of Listed Registrants.

Not applicable.

Item 6. Schedule of Investments.

Not applicable. The complete schedule of investments is included in Item 1 of this Form N-CSR.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable.

Item 8. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not applicable.

Item 10. Submission of Matters to a Vote of Security Holders.

Not applicable.

Item 11. Controls and Procedures.

(a) The registrant’s principal executive officer and principal financial officer have evaluated the registrant’s disclosure controls and procedures within 90 days of this filing and have concluded that the registrant’s disclosure controls and procedures were effective, as of that date, in ensuring that information required to be disclosed by the registrant in this Form N-CSR was recorded, processed, summarized, and reported timely.

(b) The registrant’s principal executive officer and principal financial officer are aware of no change in the registrant’s internal control over financial reporting that occurred during the registrant’s second fiscal quarter covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Exhibits.

(a)(1) The registrant’s code of ethics pursuant to Item 2 of Form N-CSR is attached.

    (2) Separate certifications by the registrant's principal executive officer and principal financial officer, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 and required by Rule 30a-2(a) under the Investment Company Act of 1940, are attached.

    (3) Written solicitation to repurchase securities issued by closed-end companies: not applicable.

(b) A certification by the registrant's principal executive officer and principal financial officer, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 and required by Rule 30a-2(b) under the Investment Company Act of 1940, is attached.

SIGNATURES
	Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment
Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.
T. Rowe Price Mid-Cap Growth Fund, Inc.
By	/s/ Edward C. Bernard
	Edward C. Bernard
	Principal Executive Officer
Date	February 19, 2008
	Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment
Company Act of 1940, this report has been signed below by the following persons on behalf of
the registrant and in the capacities and on the dates indicated.
By	/s/ Edward C. Bernard
	Edward C. Bernard
	Principal Executive Officer
Date	February 19, 2008
By	/s/ Joseph A. Carrier
	Joseph A. Carrier
	Principal Financial Officer
Date	February 19, 2008

EX-99.CERT

Item 12(a)(2).

CERTIFICATIONS 

I, Edward C. Bernard, certify that:
1.	I have reviewed this report on Form N-CSR of T. Rowe Price Mid-Cap Growth Fund;
2.	Based on my knowledge, this report does not contain any untrue statement of a material fact or omit
	to state a material fact necessary to make the statements made, in light of the circumstances under
	which such statements were made, not misleading with respect to the period covered by this report;
3.	Based on my knowledge, the financial statements, and other financial information included in this
	report, fairly present in all material respects the financial condition, results of operations, changes in
	net assets, and cash flows (if the financial statements are required to include a statement of cash
	flows) of the registrant as of, and for, the periods presented in this report;
4.	The registrant's other certifying officer(s) and I are responsible for establishing and maintaining
	disclosure controls and procedures (as defined in rule 30a-3(c) under the Investment Company Act
	of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the
	Investment Company Act of 1940) for the registrant and have:
	(a) Designed such disclosure controls and procedures, or caused such disclosure controls and
		procedures to be designed under our supervision, to ensure that material information relating to
		the registrant, including its consolidated subsidiaries, is made known to us by others within those
		entities, particularly during the period in which this report is being prepared;
	(b) Designed such internal control over financial reporting, or caused such internal control over
		financial reporting to be designed under our supervision, to provide reasonable assurance
		regarding the reliability of financial reporting and the preparation of financial statements for
		external purposes in accordance with generally accepted accounting principles;
	(c)	Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in
		this report our conclusions about the effectiveness of the disclosure controls and procedures, as of
		a date within 90 days prior to the filing date of this report based on such evaluation; and
	(d)	Disclosed in this report any change in the registrant’s internal control over financial reporting that
		occurred during the second fiscal quarter of the period covered by this report that has materially
		affected, or is reasonably likely to materially affect, the registrant’s internal control over financial
		reporting; and
5.	The registrant's other certifying officer(s) and I have disclosed to the registrant's auditors and the
	audit committee of the registrant's board of directors (or persons performing the equivalent
	functions):
	(a)	All significant deficiencies and material weaknesses in the design or operation of internal control
		over financial reporting which are reasonably likely to adversely affect the registrant's ability to
		record, process, summarize, and report financial information; and
	(b)	Any fraud, whether or not material, that involves management or other employees who have a
		significant role in the registrant's internal control over financial reporting.

Date:	February 19, 2008	/s/ Edward C. Bernard
		Edward C. Bernard
		Principal Executive Officer

CERTIFICATIONS 

I, Joseph A. Carrier, certify that:
1.	I have reviewed this report on Form N-CSR of T. Rowe Price Mid-Cap Growth Fund;
2.	Based on my knowledge, this report does not contain any untrue statement of a material fact or omit
	to state a material fact necessary to make the statements made, in light of the circumstances under
	which such statements were made, not misleading with respect to the period covered by this report;
3.	Based on my knowledge, the financial statements, and other financial information included in this
	report, fairly present in all material respects the financial condition, results of operations, changes in
	net assets, and cash flows (if the financial statements are required to include a statement of cash
	flows) of the registrant as of, and for, the periods presented in this report;
4.	The registrant's other certifying officer(s) and I are responsible for establishing and maintaining
	disclosure controls and procedures (as defined in rule 30a-3(c) under the Investment Company Act
	of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the
	Investment Company Act of 1940) for the registrant and have:
	(a) Designed such disclosure controls and procedures, or caused such disclosure controls and
		procedures to be designed under our supervision, to ensure that material information relating to
		the registrant, including its consolidated subsidiaries, is made known to us by others within those
		entities, particularly during the period in which this report is being prepared;
	(b) Designed such internal control over financial reporting, or caused such internal control over
		financial reporting to be designed under our supervision, to provide reasonable assurance
		regarding the reliability of financial reporting and the preparation of financial statements for
		external purposes in accordance with generally accepted accounting principles;
	(c)	Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in
		this report our conclusions about the effectiveness of the disclosure controls and procedures, as of
		a date within 90 days prior to the filing date of this report based on such evaluation; and
	(d)	Disclosed in this report any change in the registrant’s internal control over financial reporting that
		occurred during the second fiscal quarter of the period covered by this report that has materially
		affected, or is reasonably likely to materially affect, the registrant’s internal control over financial
		reporting; and
5.	The registrant's other certifying officer(s) and I have disclosed to the registrant's auditors and the
	audit committee of the registrant's board of directors (or persons performing the equivalent
	functions):
	(a)	All significant deficiencies and material weaknesses in the design or operation of internal control
		over financial reporting which are reasonably likely to adversely affect the registrant's ability to
		record, process, summarize, and report financial information; and
	(b)	Any fraud, whether or not material, that involves management or other employees who have a
		significant role in the registrant's internal control over financial reporting.

Date:	February 19, 2008	/s/ Joseph A. Carrier
		Joseph A. Carrier
		Principal Financial Officer

EX-99.906 CERT

Item 12(b).
CERTIFICATION UNDER SECTION 906 OF SARBANES-OXLEY ACT OF 2002
Name of Issuer: T. Rowe Price Mid-Cap Growth Fund
In connection with the Report on Form N-CSR for the above named Issuer, the undersigned hereby
certifies, to the best of his knowledge, that:
1.	The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities
	Exchange Act of 1934;
2.	The information contained in the Report fairly presents, in all material respects, the financial
	condition and results of operations of the Issuer.
Date: February 19, 2008		/s/ Edward C. Bernard
		Edward C. Bernard
		Principal Executive Officer
Date: February 19, 2008		/s/ Joseph A. Carrier
		Joseph A. Carrier
		Principal Financial Officer

EX-99.CODE ETH

CODE OF ETHICS FOR PRINCIPAL EXECUTIVE AND SENIOR FINANCIAL     

OFFICERS OF THE PRICE FUNDS     

UNDER THE SARBANES-OXLEY ACT OF 2002     

I. General Statement. This Code of Ethics (the “Price Funds S-O Code”) has been designed 

to bring the Price Funds into compliance with the applicable requirements of the Sarbanes-Oxley 

Act of 2002 (the “Act”) rules promulgated by The Securities and Exchange Commission 

thereunder (“Regulations”). The Price Funds S-O Code applies solely to the Principal 

Executive Officer, Principal Financial Officer, Principal Accounting Officer or Controller of, or 

persons performing similar functions for, a Price Fund (whether such persons are employed by a 

Price Fund or third party) (“Covered Officers”). The “Price Funds” shall include each mutual 

fund that is managed, sponsored and distributed by affiliates of T. Rowe Price Group, Inc. 

(“Group”). The investment managers to the Price Funds will be referred to as the “Price Fund 

Advisers.” A list of Covered Officers is attached as Exhibit A. 

The Price Fund Advisers have, along with their parent, T. Rowe Price Group, Inc. (“Group”) 

also maintained a comprehensive Code of Ethics and Conduct (the “Group Code”) since 1972, 

which applies to all officers, directors and employees of the Price Funds, Group and its affiliates. 

As mandated by the Act, Group has adopted a Code (the “Group S-O Code”), similar to the 

Price Funds S-O Code, which applies solely to its principal executive and senior financial 

officers. The Group S-O Code and the Price Funds S-O Code will be referred to collectively as 

the “S-O Codes”. 

The Price Funds S-O Code has been adopted by the Price Funds in accordance with the Act and 

Regulations thereunder and will be administered in conformity with the disclosure requirements 

of Item 2 of Form N-CSR. The S-O Codes are attachments to the Group Code. In many respects 

the S-O Codes are supplementary to the Group Code, but the Group Code is administered 

separately from the S-O Codes, as the S-O Codes are from each other. 

II. Purpose of the Price Funds S-O Code. The purpose of the Price Funds S-O Code, as 

mandated by the Act and the Regulations, is to establish standards that are reasonably designed 

to deter wrongdoing and to promote: 

             Ethical Conduct. Honest and ethical conduct, including the ethical handling of actual or 

             apparent conflicts of interest between personal and professional relationships. 

             Disclosure. Full, fair, accurate, timely and understandable disclosure in reports and 

             documents that the Price Funds file with, or submit to, the SEC and in other public 

             communications made by the Price Funds. 

             Compliance. Compliance with applicable governmental laws, rules and regulations. 

             Reporting of Violations. The prompt internal reporting of violations of the Price Funds 

             S-O Code to an appropriate person or persons identified in the Price Funds S-O Code. 

             Accountability. Accountability for adherence to the Price Funds S-O Code. 

III. Covered Officers Should Handle Ethically Actual and Apparent Conflicts of Interest. 

Overview. Each Covered Officer owes a duty to the Price Funds to adhere to a high standard of 

honesty and business ethics and should be sensitive to situations that may give rise to actual as 

well as apparent conflicts of interest. 

A “conflict of interest” occurs when a Covered Officer’s private interest interferes with the 

interests of, or his or her service to, the Price Funds. For example, a conflict of interest would 

arise if a Covered Officer, or a member of his or her family, receives improper personal benefits 

as a result of his or her position with a Price Fund. 

Certain conflicts of interest covered by the Price Funds S-O Code arise out of the relationships 

between Covered Officers and the Price Funds and may already be subject to provisions 

regulating conflicts of interest in the Investment Company Act of 1940 (“Investment Company 

Act”), the Investment Advisers Act of 1940 (“Investment Advisers Act”) and the Group Code. 

For example, Covered Officers may not individually engage in certain transactions (such as the 

purchase or sale of securities or other property) with a Price Fund because of their status as 

“affiliated persons” of a Price Fund. The compliance programs and procedures of the Price 

Funds and Price Fund Advisers are designed to prevent, or identify and correct, violations of 

these provisions. 

Although typically not presenting an opportunity for improper personal benefit, conflicts arise 

from, or as a result of, the contractual relationship between a Price Fund and its Price Fund 

Adviser (and its affiliates) of which the Covered Officers may also be officers or employees. As 

a result, the Price Funds S-O Code recognizes that the Covered Officers will, in the normal 

course of their duties (whether formally for the Price Funds or for the Price Fund Advisers, or for 

both), be involved in establishing policies and implementing decisions which will have different 

effects on these entities. The participation of the Covered Officers in such activities is inherent 

in the contractual relationship between each Price Fund and its respective Price Fund Adviser. 

Such participation is also consistent with the performance by the Covered Officers of their duties 

as officers of the Price Funds and, if consistent with the provisions of the Investment Company 

Act and the Investment Advisers Act, it will be deemed to have been handled ethically. 

Other conflicts of interest are covered by the Price Funds S-O Code, even if these conflicts of 

interest are not addressed by or subject to provisions in the Investment Company Act and the 

Investment Advisers Act. 

Whenever a Covered Officer is confronted with a conflict of interest situation where he or she is 

uncertain as to the appropriate action to be taken, he or she should discuss the matter with the 

Chairperson of Group’s Ethics Committee or another member of the Committee. 

Handling of Specific Types of Conflicts. Each Covered Officer (and close family members) 

must not: 

              Entertainment. Accept entertainment from any company with which any Price 

              Fund or any Price Fund Adviser has current or prospective business dealings, 

              including portfolio companies, unless such entertainment is in full compliance 

              with the policy on entertainment as set forth in the Group Code. 

              Gifts. Accept any gifts, except as permitted by the Group Code. 

               Improper Personal Influence. Use his or her personal influence or personal 

               relationships improperly to influence investment decisions, brokerage allocations 

               or financial reporting by the Price Funds to the detriment of any one or more of 

               the Price Funds. 

               Taking Action at the Expense of a Price Fund. Cause a Price Fund to take 

               action, or fail to take action, for the personal benefit of the Covered Officer rather 

               than for the benefit of one or more of the Price Funds. 

               Misuse of Price Funds’ Transaction Information. Use knowledge of portfolio 

               transactions made or contemplated for a Price Fund or any other clients of the 

               Price Fund Advisers to trade personally or cause others to trade in order to take 

               advantage of or avoid the market impact of such portfolio transactions. 

               Outside Business Activities. Engage in any outside business activity that 

               detracts from a Covered Officer’s ability to devote appropriate time and attention 

               to his or her responsibilities to a Price Fund. 

               Service Providers. Excluding Group and its affiliates, have any ownership 

               interest in, or any consulting or employment relationship with, any of the Price 

               Funds’ service providers, except that an ownership interest in public companies is 

               permitted 

               Receipt of Payments. Have a direct or indirect financial interest in commissions, 

               transaction charges, spreads or other payments paid by a Price Fund for effecting 

               portfolio transactions or for selling or redeeming shares other than an interest 

               (such as compensation or equity ownership) arising from the Covered Officer’s 

               employment by Group or any of its affiliates. 

               Service as a Director or Trustee. Serve as a director, trustee or officer of any 

               public or private company or a non-profit organization that issues securities 

               eligible for purchase by any of the Price Funds, unless approval is obtained as 

               required by the Group Code. 

IV. Covered Officers’ Specific Obligations and Accountabilities.   

               A. Disclosure Requirements and Controls. Each Covered Officer must 

               familiarize himself or herself with the disclosure requirements (Form N-1A registration 

               statement, proxy (Schedule 14A), shareholder reports, Forms N-SAR, N-CSR, etc.) 

               applicable to the Price Funds and the disclosure controls and procedures of the Price 

               Fund and the Price Fund Advisers. 

               B. Compliance with Applicable Law. It is the responsibility of each Covered 

               Officer to promote compliance with all laws, rules and regulations applicable to the Price 

               Funds and the Price Fund Advisers. Each Covered Officer should, to the extent 

               appropriate within his or her area of responsibility, consult with other officers and 

               employees of the Price Funds and the Price Fund Advisers and take other appropriate 

               steps with the goal of promoting full, fair, accurate, timely and understandable disclosure 

               in the reports and documents the Price Funds file with, or submit to, the SEC, and in 

               other public communications made by the Price Funds. 

               C. Fair Disclosure. Each Covered Officer must not knowingly misrepresent, or 

               cause others to misrepresent, facts about a Price Fund to others, whether within or 

               outside the Price organization, including to the Price Fund’s directors and auditors, and 

               to governmental regulators and self-regulatory organizations. 

               D. Initial and Annual Affirmations. Each Covered Officer must:

                     1. Upon adoption of the Price Funds S-O Code (or thereafter, as applicable, upon 

                     becoming a Covered Officer), affirm in writing that he or she has received, read, 

                     and understands the Price Funds S-O Code. 

                     2. Annually affirm that he or she has complied with the requirements of the Price 

                     Funds S-O Code. 

               E. Reporting of Material Violations of the Price Funds S-O Code. If a 

               Covered Officer becomes aware of any material violation of the Price Funds S-O Code 

               or laws and governmental rules and regulations applicable to the operations of the 

               Price Funds, he or she must promptly report the violation (“Report”) to the Chief 

               Legal Counsel of the Price Funds (“CLC”). Failure to report a material violation will 

               be considered itself a violation of the Price Funds S-O Code. The CLC is identified in 

               the attached Exhibit B. 

               It is the Price Funds policy that no retaliation or other adverse action will be taken 

               against any Covered Officer or other employee of a Price Fund, a Price Fund Adviser 

               or their affiliates based upon any lawful actions of the Covered Officer or employee 

               with respect to a Report made in good faith. 

               F. Annual Disclosures. Each Covered Officer must report, at least annually, all 

               affiliations or other relationships as called for in the “Annual Questionnaire for 

               Executive Officers and/or Employee Directors/Trustees of Group and the Price Funds.” 

V. Administration of the Price Funds S-O Code. The Ethics Committee is responsible for 

administering the Price Funds S-O Code and applying its provisions to specific situations in 

which questions are presented. 

               A. Waivers and Interpretations. The Chairperson of the Ethics Committee has 

               the authority to interpret the Price Funds S-O Code in any particular situation and to 

               grant waivers where justified, subject to the approval of the Joint Audit Committee of 

               the Price Funds. All material interpretations concerning Covered Officers will be 

               reported to the Joint Audit Committee of the Price Funds at its next meeting. Waivers, 

               including implicit waivers, to Covered Officers will be publicly disclosed as required 

               in the Instructions to N-CSR. Pursuant to the definition in the Regulations, an implicit 

               waiver means a Price Fund’s failure to take action within a reasonable period of time 

               regarding a material departure from a provision of the Price Funds S-O Code that has 

               been made known to an “executive officer” (as defined in Rule 3b-7 under the 

               Securities Exchange Act of 1934) of a Price Fund. An executive officer of a Price 

               Fund includes its president and any vice-president in charge of a principal business 

               unit, division or function. 

               B. Violations/Investigations. The following procedures will be followed in 

               investigating and enforcing the Price Funds S-O Code: 

                     1. The CLC will take or cause to be taken appropriate action to 

                     investigate any potential or actual violation reported to him or her. 

                     2. The CLC, after consultation if deemed appropriate with Outside 

                     Counsel to the Price Funds, will make a recommendation to the 

                     appropriate Price Funds Board regarding the action to be taken with 

                     regard to each material violation. Such action could include any of the 

                     following: a letter of censure or suspension, a fine, a suspension of trading 

                     privileges or termination of officership or employment. In addition, the 

                     violator may be required to surrender any profit realized (or loss avoided) 

                     from any activity that is in violation of the Price Funds S-O Code. 

VI. Amendments to the Price Funds S-O Code. Except as to the contents of Exhibit A and 

Exhibit B, the Price Funds S-O Code may not be materially amended except in written form, 

which is specifically approved or ratified by a majority vote of each Price Fund Board, including 

a majority of the independent directors on each Board. 

VII. Confidentiality. All reports and records prepared or maintained pursuant to the Price 

Funds S-O Code will be considered confidential and shall be maintained and protected 

accordingly. Except as otherwise required by law, the Price Funds S-O Code or as necessary in 

connection with regulations under the Price Funds S-O Code, such matters shall not be disclosed 

to anyone other than the directors of the appropriate Price Fund Board, Outside Counsel to the 

Price Funds, members of the Ethics Committee and the CLC and authorized persons on his or 

her staff. 

Preparation Date: 9/30/03 

Adoption Date:     10/22/03

Exhibit A 

Persons Covered by the Price Funds S-O Code of Ethics 

Edward C. Bernard, Chairman and Chief Executive Officer 

Joseph A. Carrier, Treasurer and Chief Financial Officer 

Exhibit B 

Chief Legal Counsel to the Price Funds 

Henry H. Hopkins