UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act File Number: 811-06665

T. Rowe Price Mid-Cap Growth Fund, Inc.

(Exact name of registrant as specified in charter)

100 East Pratt Street, Baltimore, MD 21202

(Address of principal executive offices)

David Oestreicher

100 East Pratt Street, Baltimore, MD 21202

(Name and address of agent for service)

Registrant’s telephone number, including area code: (410) 345-2000

Date of fiscal year end: December 31

Date of reporting period: December 31, 2017

The views and opinions in this report were current as of December 31, 2017. 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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What had been an unloved and largely ignored market rally began to gather widespread attention in 2017 as every other day seemed to bring news of a record close on Wall Street (in truth, the S&P 500 notched 62 record highs during the year—still not shabby). The bull market that began in March 2009 is now second in duration and magnitude, trailing only the bull market of the 1990s, which culminated with the Internet bubble at the turn of the millennium. As we describe below, we are among a shrinking subset of investment professionals who were managing money during those years, and we know how these parties end. As a result, the fund’s positioning is increasingly cautious, and this has weighed on our relative performance in recent months. As we discuss below, however, we believe that experience and caution can be valuable in times of market exuberance.

The Mid-Cap Growth Fund returned 24.86% in the 12 months ended December 31, 2017, with 8.93% of the gain coming in the second half of the period. The fund slightly trailed its benchmark and peer group average due to underperformance in the second half of 2017. (Returns for the Advisor, R, and I Class shares varied slightly, reflecting their different fee structures.) Nevertheless, the fund remained favorably ranked relative to its competitors over all time periods and is the top-ranked fund since its inception in 1992. (Based on cumulative total return, Lipper ranked the Mid-Cap Growth Fund 182 of 383, 37 of 356, 19 of 316, 5 of 227, and 1 of 21 funds in the mid-cap growth funds category for the 1-, 3-, 5-, and 10-year and since-inception periods ended December 31, 2017, respectively. Past performance cannot guarantee future results.)

Stocks continued their remarkably steady ascent in the six months since our last report, with the major indexes rarely swinging by more than 1% on a daily basis and volatility measures touching all-time lows. Signs that the economy had finally shifted into a higher gear deserve significant credit for the market’s further leg upward. After slowing in the first quarter, U.S. gross domestic product growth picked up substantially in the second and third quarters, recording its best back-to-back performance in three years. The labor market remained especially strong, with the unemployment rate falling to its lowest level since December 2000. Consumer confidence also reached its highest level in 17 years. Not surprisingly, consumers shopped (or at least clicked) aggressively during the holiday season, resulting in robust sales for most retailers.

Washington deserved substantial credit for the gains late in the year. Investors were skeptical throughout much of the fall that congressional Republicans would be able to pass their promised tax reform bill, particularly after their repeated failures to repeal the Affordable Care Act. Markets began to rally in late November as a reform plan moved through the Senate, where the hurdles to its passage seemed highest, and news of the final compromise bill in mid-December took indexes to their highs for the year. The U.S. corporate tax code was long overdue for an overhaul as our tax rates had become among the highest in the world, discouraging companies from investing here, incentivizing elaborate maneuvers to recognize income in lower tax jurisdictions, and even encouraging some to move their headquarters to low-tax domiciles.

Our sense is that markets are overreacting to the tax bill, however. A tight labor market, rising commodity prices, increased capital spending, and old-fashioned competition are all likely to siphon away much of the tax savings for most firms over time. We believe that the consensus view that most of the windfall will be returned to shareholders rather than to other stakeholders is far too simplistic. We would also note that, as with much that happens in Washington these days, Congress did not have the fortitude to offset corporate tax cuts by closing enough tax loopholes elsewhere, thus widening the likely deficits in future years. Nevertheless, in the short term, cutting taxes in an already booming economy is very stimulative and appears to have triggered animal spirits on Main Street and in corporate executive suites. If consumers were confident, many management teams ended the year downright giddy.

Ebullience in the C-suite seemed to be paired with a growing sense of euphoria on Wall Street. Markets became increasingly driven by momentum late in the year as investors poured into stocks that had already performed best. Having spurned equities in favor of bonds throughout much of the bull market, individual investors began returning to the market, focusing their buying on index-tracking exchange-traded funds (ETFs)—themselves a form of momentum-driven, valuation-agnostic investing as their composition favors companies whose stocks have already done well. Without knowing it, many Americans became heavy investors in the proverbial “FANG”—Facebook, Amazon, Netflix, and Google (Alphabet)—and other highly valued tech companies.

Having been at the epicenter of events over the previous several years, the Federal Reserve faded a bit from view in late 2017. The central bank’s decision to raise rates by another quarter point in December took no one by surprise, and Fed Governor Jerome Powell’s appointment to replace his close ally Janet Yellen as Fed chair in early 2018 signaled a continued go-slow approach in raising rates. Meanwhile, the European Central Bank and the Bank of Japan continued their massive asset purchases, placing downward pressure on long-term rates globally. The easy money burner remained on, gently heating up prices for a wide range of assets, from bonds to real estate to stocks. But like the proverbial frog sitting contentedly in a slowly warming pot, few stock investors seemed to notice that things, in general, were getting a bit hot. Indeed, the speculative fervor in Bitcoin made the “melt-up,” as many are calling the relentless rise in equity prices, feel downright prosaic in comparison. Investors in stocks with little valuation support could point out that at least they weren’t investing in alternative currencies, assets with no notional value at all.

In a risk-seeking environment, where virtually everything appeared expensive, investors did not single out a lone sector, as was the case with technology stocks in 1999 or housing in 2006. Indeed, technology stocks only marginally outperformed the Russell Midcap Growth Index in the second half of the year and trailed both financial and industrial shares. The environment generally favored growth stocks, and the mid-cap growth sector outperformed its value counterpart considerably throughout the year. But large-cap growth companies were the stellar performers of 2017, continuing the trend we’ve seen in recent years.

The unique breadth in the market’s advance in 2017 was reflected in the small number of our holdings that actually declined; in fact, no sector detracted on an overall basis. Technology stocks, which represent about one-fifth of the portfolio, contributed the most. In our semiannual letter, we mentioned the strong performance of Microchip Technology, a maker of microcontrollers that benefited from the very successful integration of its acquisition of Atmel, as well as longtime holding Fiserv, a provider of financial processing and mobile payments services. Services providers Global Payments and Vantiv also performed well, as did Red Hat, the dominant purveyor of open-source Linux-based software services. Cybersecurity firm Palo Alto Networks was a modest disappointment before we eliminated our position early in the year. (Please refer to the fund’s portfolio of investments for a complete list of our holdings and the amount each represents in the portfolio.)

As longtime shareholders know, the fund has long emphasized the industrials and business services sector, where we have been able to find companies growing at steady, if not spectacular, rates trading at reasonable valuations. Our large position in aerospace and defense firm Textron was our top contributor in this segment as the business jet market showed signs of improvement, helping sales of its Citation and Beechcraft aircraft. Tests conducted with the Air Force drew attention to the company’s new Scorpion military jet, an inexpensive light attack and reconnaissance plane with considerable potential. Diversified defense supplier Harris also performed well after posting better-than-expected revenue growth driven by improving demand for its tactical radios. Longtime holding IDEX, a provider of flow pumps, meters, and other fluid control products, boosted our results after repeatedly beating investors’ earnings expectations.

As usual, our health care holdings provided widely disparate results. We discussed the strong performance of catheter specialist Teleflex and specialty contact lens maker Cooper Companies in our semiannual letter. Analytical instrument maker Agilent Technologies was another major contributor after handily beating revenue and margins forecasts. On the negative side, Envision Healthcare, which provides outsourced physicians for hospital emergency rooms and a range of other services, was the portfolio’s largest detractor in 2017 as it struggled to integrate a large merger. The company has announced a strategic review, and we believe it is contemplating whether a major overhaul of its operations might best be accomplished as a private company.

Our consumer holdings provided mixed returns as the threat of “Amazonification” cast a wide shadow over the sector. With Amazon yet to unveil its own hotels and cruise ships, our leisure holdings were free to benefit from healthier consumer spending, particularly for “experiences” rather than goods. Marriott and Norwegian Cruise Line Holdings, both mentioned in our last letter, were particularly strong. However, the Amazon threat precipitated significant strategy shifts at many retailers, including Dick’s Sporting Goods. We had thought that, like Best Buy in consumer electronics, Dick’s could benefit as the last major terrestrial retailer standing in its sector. While we still believe this to be the case, the company’s growth trajectory has been severely compromised, and we decided to eliminate it from the portfolio. Amazon also poses a long-term threat to the auto parts retail and distribution sector, but the primary reason we sold long-time holding AutoZone late in the year was its struggle to execute its strategy to market to professional service and repair shops.

We have a smaller weighting in financials, where our investments are clustered in capital markets and insurance. Our top performer here was Cboe Global Markets, the largest U.S. options exchange. The company recently merged with Bats Global Markets, the second-largest exchange by volume, and its stock surged on early indications that the combination was working as planned. We anticipate that the combination of Cboe’s proprietary products with Bat’s global technology platform will yield significant synergies over time. Title insurer FNF and insurance broker Willis Towers Watson were also strong performers. The latter is also the product of a recent merger that seems to be functioning well.

Our management style is typically to purchase new positions when good companies misstep or the market overreacts to what we view as temporary issues. This has happened rarely in the last year, posing real challenges for us. We did initiate positions in Dunkin Brands, based largely on our expectation that its new chief operating officer will strengthen the concept’s appeal, and in Ulta Beauty, whose stock fell as its exceptionally high same-store sales growth moderated. We believe the latter will continue to capture market share as vendors seek new partners to offset sales declines at department stores. In the case of cybersecurity vendor Symantec, growth has slowed over the last few years, but demand for cybersecurity continues to grow quickly as corporations, governments, and individuals seek to protect their valuable data. Its 2016 acquisition of rival Blue Coat brought with it a new CEO who we believe will streamline the company and develop innovative products more rapidly. We also added to our position in Colfax. This industrial company has struggled in recent years, but we believe that its efforts to restructure its businesses under the tutelage of a board and a management system that are closely related to Danaher, a stellar former holding in our fund, are beginning to bear fruit.

In recent years, we have written repeatedly about “froth” in isolated segments of the market. If we are to stick with that analogy, we might say that the bits of froth are converging as valuations have increased more broadly across industry sectors. This begs the logical question: Has the froth now coalesced into a bubble?

Of course, analogies can take us only so far, and even more quantitative descriptions of market excess leave some room for doubt. By our reckoning, stock prices appear to be about 15% to 20% above normal. The price-to-earnings ratio on the S&P 500 ended 2017 hovering around 19 on a forward basis, its highest level since the start of the last decade but well below its peak of about 27 at the height of the dot-com bubble. We are mindful that elevated valuations do not predict the timing of declines. Nevertheless, they are a forward indicator of higher risk and lower future returns.

Properly defining a bubble also relies on calling out a series of market characteristics that are not easily captured in numbers. No bubble is exactly the same; though, to paraphrase Mark Twain, they do rhyme. Investor euphoria is a necessary component, as is the absence of fear. Indeed, the only fear common on Wall Street during bubbles is the fear of being left behind—a concern we are increasingly hearing from fellow investment professionals. On balance, we do not believe that the current stock environment is extreme enough to merit bubble status, but we believe it could if the melt-up persists much longer.

We observe that high valuations are present not only in the U.S. stock market but in most asset classes. In fact, bonds, some of which still trade at negative yields, may well be more overvalued than stocks. As we have written before, the current situation is the result of the extraordinary liquidity injected into the global economy by the various central banks in response to the great financial crisis in 2008–2009. Even though that crisis is long past, the central banks have continued to fight the last war, as it were, and the consequence is inflation in most asset classes globally. The longer this persists, the greater the consequences are likely to be when the market recalibrates.

As our longtime shareholders know, our fund fared better than the vast majority of its peers in the two bubbles in recent market history, although they were hardly pleasant experiences. In the tech bubble that peaked in 2000, we vastly underperformed over the preceding several quarters. Our decision to skip the party on the way up was not taken lightly, and there were many sleepless nights in 1999. We were broadly criticized by the press, by clients, and even by younger colleagues. In our letter to you in the summer of 2012, we looked back on this period: “On March 6, 2000, this fund and your manager were featured in a Wall Street Journal article describing how T. Rowe Price had become a “tradition-bound firm” that had been slow to embrace the growing importance of technology stocks. As the article noted, the fund’s 23.8% gain in 1999 seriously lagged the 72.9% return of the average mid-cap growth fund.”

As it turned out, the moves we made to protect capital in this period, as excruciating as they seemed at the time, paid off over the next few years. Other mid-cap managers chose to run with the crowd, destroyed their clients’ capital, and were driven from the investment business. With our losses modest in comparison, we were able to search among the rubble and pick up many outstanding growth companies at compelling valuations.

The choices we faced in the real estate bubble of the mid-2000s were not as stark given that mid-cap growth stocks were not at the center of the turmoil, and we certainly did not foresee the coming global financial crisis. Nevertheless, we sold most of our real estate and credit-sensitive issues early, which helped our subsequent performance.

Even in these two bubbles, pockets of reasonable or even cheap valuations offered shelter, as was the case with “old economy” industrials and business services stocks in the late 1990s. In contrast, the current melt-up has the unusual characteristic of broad overvaluation across many market sectors. Not only that, but the less volatile, steady growth stocks we have favored over the years are now among the more expensive stocks in the market relative to their growth rates. Perhaps investors are acknowledging an expensive market and would prefer to go into a downturn owning the best companies regardless of valuation. In our last letter, we discussed how the valuation-insensitive nature of index investing may be what is driving the market’s relentless and steady move higher. The flip side of this phenomenon is that there are now fewer active, valuation-sensitive investors ready to step in when stocks experience a major correction, as will happen eventually. This could exacerbate any future declines. Unlike the last two bubbles, there seem to be few places to hide.

We could retire. A generation of top investors did just that in 1999. At ages 59 and 55, respectively, this is a viable option. (We like to think that our wives would favor such a choice, but we also keep in mind the advice given to a mentor of ours whose wife always respected their vow of “for better or worse” while adding the caveat “but never for lunch.”) However, we both feel that we have acquired some kernels of wisdom over the years, and investing is a profession where experience and age can be an attribute.

Alternatively, we could aggressively raise cash levels. This is possible, and in 1999, we had 8% cash reserves at year-end. It helped somewhat in the downturn, but, in reality, cash levels would really need to be much higher to have a large impact. Some might say that cash levels of 5% or more in a strategy charged with investing in mid-cap growth issues is a dereliction of duty. We think that’s a bit extreme, but in the end, we believe that cash levels are a decision our clients should make. Our job is to invest in mid-cap growth stocks because that is what our clients are paying us to do.

The third option is to continue with what we’re currently doing: staying fairly fully invested while trying to invest incrementally more cautiously as the market relentlessly rises. This involves paring back the most expensive stocks in our portfolio and buying issues that are still expensive historically but less pricey on a relative basis; orienting the portfolio toward less cyclical and less market-sensitive holdings; and moderating positions in companies that we feel have poor underlying profitability.

For the moment, we are pursuing this third approach, but not without great trepidation. We are not at all hesitant, however, about the fundamental investment process we have executed consistently through the years, and we appreciate your continued confidence in our ability to guide your fund through a range of market environments. We look forward to reporting again on our efforts in six months.

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

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.

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.

Gross domestic product: The total market value of all goods and services produced in a country in a given year.

Lipper indexes: Fund benchmarks that consist of a small number of the largest mutual funds in a particular category as defined 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 forecast 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 forecast growth values.

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

Note: Russell Investment Group is the source and owner of the trademarks, service marks, and copyrights related to the Russell indexes. Russell^®is a trademark of Russell Investment Group.

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.

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 four 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, and I Class shares are available to institutionally oriented clients and impose no 12b-1 or administrative fee payment. 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 on 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 on 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 account service fee of $20, generally for accounts with less than $10,000. The fee is waived for any investor whose T. Rowe Price mutual fund accounts total $50,000 or more; accounts electing to receive electronic delivery of account statements, transaction confirmations, prospectuses, and shareholder reports; or accounts of an investor who is a T. Rowe Price Personal Services or Enhanced Personal Services client (enrollment in these programs generally requires T. Rowe Price assets of at least $250,000). 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.

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 four classes of shares: the Mid-Cap Growth Fund (Investor Class), the Mid-Cap Growth Fund–Advisor Class (Advisor Class), the Mid-Cap Growth Fund–R Class (R Class), and the Mid-Cap Growth Fund–I Class (I Class). 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. I Class shares generally are available only to investors meeting a $1,000,000 minimum investment or certain other criteria. 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; the Investor and I Classes do not pay Rule 12b-1 fees. 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.

Basis of Preparation The fund is an investment company and follows accounting and reporting guidance in the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 (ASC 946). The accompanying financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (GAAP), including, but not limited to, ASC 946. GAAP requires the use of estimates made by management. Management believes that estimates and valuations are appropriate; however, actual results may differ from those estimates, and the valuations reflected in the accompanying financial statements may differ from the value ultimately realized upon sale or maturity.

Investment Transactions, Investment Income, and Distributions Investment transactions are accounted for on the trade date basis. Income and expenses are recorded on the accrual basis. Realized gains and losses are reported on the identified cost basis. Dividends received from mutual fund investments are reflected as dividend income; capital gain distributions are reflected as realized gain/loss. Earnings on investments recognized as partnerships for federal income tax purposes reflect the tax character of such earnings. Dividend income and capital gain distributions are recorded on the ex-dividend date. Income tax-related interest and penalties, if incurred, are recorded as income tax expense. Income distributions are declared and paid by each class annually. Distributions to shareholders are recorded on the ex-dividend date. A capital gain distribution may also be declared and paid by the fund annually.

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 respective date of such transaction. The portion of the results of operations attributable to changes in foreign exchange rates on investments is not bifurcated from the portion attributable to changes in market prices. 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 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. To the extent any expenses are waived or reimbursed in accordance with an expense limitation (see Note 5), the waiver or reimbursement is charged to the applicable class or allocated across the classes in the same manner as the related expense. The Advisor Class and R Class each pay Rule 12b-1 fees, in an amount not exceeding 0.25% and 0.50%, respectively, of the class’s average daily net assets.

Rebates 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 $284,000 for the year ended December 31, 2017.

In-Kind Redemptions In accordance with guidelines described in the fund’s prospectus, and when considered to be in the best interest of all shareholders, the fund may distribute portfolio securities rather than cash as payment for a redemption of fund shares (in-kind redemption). 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, 2017, the fund realized $247,802,000 of net gain on $522,476,000 of in-kind redemptions.

New Accounting Guidance In March 2017, the FASB issued amended guidance to shorten the amortization period for certain callable debt securities, held at a premium. The guidance is effective for fiscal years and interim periods beginning after December 15, 2018. Adoption will have no effect on the fund’s net assets or results of operations.

On August 1, 2017, the fund implemented amendments to Regulation S-X, issued by the Securities and Exchange Commission, which require standardized, enhanced disclosures, particularly related to derivatives, in investment company financial statements. Adoption had no effect on the fund’s net assets or results of operations.

Indemnification In the normal course of business, the fund may provide indemnification in connection with its officers and directors, service providers, and/or private company investments. The fund’s maximum exposure under these arrangements is unknown; however, the risk of material loss is currently considered to be remote.

The fund’s financial instruments are valued and each class’s net asset value (NAV) per share is computed at the close of the New York Stock Exchange (NYSE), normally 4 p.m. ET, each day the NYSE is open for business. However, the NAV per share may be calculated at a time other than the normal close of the NYSE if trading on the NYSE is restricted, if the NYSE closes earlier, or as may be permitted by the SEC.

Fair Value The fund’s financial instruments are reported at fair value, which GAAP defines as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The T. Rowe Price Valuation Committee (the Valuation Committee) is an internal committee that has been delegated certain responsibilities by the fund’s Board of Directors (the Board) to ensure that financial instruments are appropriately priced at fair value in accordance with GAAP and the 1940 Act. Subject to oversight by the Board, the Valuation Committee develops and oversees pricing-related policies and procedures and approves all fair value determinations. Specifically, the Valuation Committee establishes procedures to value securities; determines pricing techniques, sources, and persons eligible to effect fair value pricing actions; oversees the selection, services, and performance of pricing vendors; oversees valuation-related business continuity practices; and provides guidance on internal controls and valuation-related matters. The Valuation Committee reports to the Board and has representation from legal, portfolio management and trading, operations, risk management, and the fund’s treasurer.

Various valuation techniques and inputs are used to determine the fair value of financial instruments. GAAP establishes the following fair value hierarchy that categorizes the inputs used to measure fair value:

Level 1 – quoted prices (unadjusted) in active markets for identical financial instruments that the fund can access at the reporting date

Level 2 – inputs other than Level 1 quoted prices that are observable, either directly or indirectly (including, but not limited to, quoted prices for similar financial instruments in active markets, quoted prices for identical or similar financial instruments in inactive markets, interest rates and yield curves, implied volatilities, and credit spreads)

Observable inputs are developed using market data, such as publicly available information about actual events or transactions, and reflect the assumptions that market participants would use to price the financial instrument. Unobservable inputs are those for which market data are not available and are developed using the best information available about the assumptions that market participants would use to price the financial instrument. GAAP requires valuation techniques to maximize the use of relevant observable inputs and minimize the use of unobservable inputs. When multiple inputs are used to derive fair value, the financial instrument is assigned to the level within the fair value hierarchy based on the lowest-level input that is significant to the fair value of the financial instrument. Input levels are not necessarily an indication of the risk or liquidity associated with financial instruments at that level but rather the degree of judgment used in determining those values.

Valuation Techniques 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. OTC Bulletin Board securities are valued at the mean of the closing 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 closing bid and asked prices for domestic securities and the last quoted sale or closing price for international securities.

For valuation purposes, the last quoted prices of non-U.S. equity securities may be adjusted to reflect the fair value of such securities at the close of the NYSE. If the fund determines that developments between the close of a foreign market and the close of the NYSE will affect the value of some or all of its portfolio securities, the fund will adjust the previous quoted prices to reflect what it believes to be the fair value of the securities as of the close of the NYSE. In deciding whether it is necessary to adjust quoted prices to reflect fair value, 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 may also fair value securities in other situations, such as when a particular foreign market is closed but the fund is open. The fund uses outside pricing services to provide it with quoted prices and information to evaluate or adjust those prices. The fund cannot predict how often it will use quoted prices and how often it will determine it necessary to adjust those prices to reflect fair value. As a means of evaluating its security valuation process, the fund routinely compares quoted prices, the next day’s opening prices in the same markets, and adjusted prices.

Actively traded equity securities listed on a domestic exchange generally are categorized in Level 1 of the fair value hierarchy. Non-U.S. equity securities generally are categorized in Level 2 of the fair value hierarchy despite the availability of quoted prices because, as described above, the fund evaluates and determines whether those quoted prices reflect fair value at the close of the NYSE or require adjustment. OTC Bulletin Board securities, certain preferred securities, and equity securities traded in inactive markets generally are categorized in Level 2 of the fair value hierarchy.

Investments in mutual funds are valued at the mutual fund’s closing NAV per share on the day of valuation and are categorized in Level 1 of the fair value hierarchy. Assets and liabilities other than financial instruments, including short-term receivables and payables, are carried at cost, or estimated realizable value, if less, which approximates fair value.

Thinly traded financial instruments 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 Valuation Committee. The objective of any fair value pricing determination is to arrive at a price that could reasonably be expected from a current sale. Financial instruments fair valued by the Valuation Committee are primarily private placements, restricted securities, warrants, rights, and other securities that are not publicly traded.

Subject to oversight by the Board, the Valuation Committee regularly makes good faith judgments to establish and adjust the fair valuations of certain securities as events occur and circumstances warrant. For instance, in determining the fair value of an equity investment with limited market activity, such as a private placement or a thinly traded public company stock, the Valuation Committee considers a variety of factors, which may include, but are not limited to, the issuer’s business prospects, its financial standing and performance, recent investment transactions in the issuer, new rounds of financing, negotiated transactions of significant size between other investors in the company, relevant market valuations of peer companies, strategic events affecting the company, market liquidity for the issuer, and general economic conditions and events. In consultation with the investment and pricing teams, the Valuation Committee will determine an appropriate valuation technique based on available information, which may include both observable and unobservable inputs. The Valuation Committee typically will afford greatest weight to actual prices in arm’s length transactions, to the extent they represent orderly transactions between market participants, transaction information can be reliably obtained, and prices are deemed representative of fair value. However, the Valuation Committee may also consider other valuation methods such as market-based valuation multiples; a discount or premium from market value of a similar, freely traded security of the same issuer; or some combination. Fair value determinations are reviewed on a regular basis and updated as information becomes available, including actual purchase and sale transactions of the issue. Because any fair value determination involves a significant amount of judgment, there is a degree of subjectivity inherent in such pricing decisions, and fair value prices determined by the Valuation Committee could differ from those of other market participants. Depending on the relative significance of unobservable inputs, including the valuation technique(s) used, fair valued securities may be categorized in Level 2 or 3 of the fair value hierarchy.

Valuation Inputs The following table summarizes the fund’s financial instruments, based on the inputs used to determine their fair values on December 31, 2017:

There were no material transfers between Levels 1 and 2 during the year ended December 31, 2017.

Following is a reconciliation of the fund’s Level 3 holdings for the year ended December 31, 2017. Gain (loss) reflects both realized and change in unrealized gain/loss on Level 3 holdings during the period, if any, and is included on the accompanying Statement of Operations. The change in unrealized gain/loss on Level 3 instruments held at December 31, 2017, totaled $42,304,000 for the year ended December 31, 2017.

Consistent with its investment objective, the fund engages in the following practices to manage exposure to certain risks and/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 and may involve substantial delays and additional costs.

Securities Lending The fund may lend its securities to approved borrowers to earn additional income. Its securities lending activities are administered by a lending agent in accordance with a securities lending agreement. Security loans generally do not have stated maturity dates, and the fund may recall a security at any time. The fund receives collateral in the form of cash or U.S. government securities, valued at 102% to 105% of the value of the securities on loan. Collateral is maintained over the life of the loan in an amount not less than the value of loaned securities; any additional collateral required due to changes in security values is delivered to the fund the next business day. Cash collateral is invested in accordance with investment guidelines approved by fund management. Additionally, the lending agent indemnifies the fund against losses resulting from borrower default. Although risk is mitigated by the collateral and indemnification, 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, collateral investments decline in value, and the lending agent fails to perform. Securities lending revenue consists of earnings on invested collateral and borrowing fees, net of any rebates to the borrower, compensation to the lending agent, and other administrative costs. In accordance with GAAP, investments made with cash collateral are reflected in the accompanying financial statements, but collateral received in the form of securities is not. At December 31, 2017, there were no securities on loan.

Other Purchases and sales of portfolio securities other than short-term securities aggregated $6,799,825,000 and $8,286,391,000, respectively, for the year ended December 31, 2017.

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. Distributions determined in accordance with federal income tax regulations may differ 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 but are not adjusted for temporary differences.

The fund files U.S. federal, state, and local tax returns as required. The fund’s tax returns are subject to examination by the relevant tax authorities until expiration of the applicable statute of limitations, which is generally three years after the filing of the tax return but which can be extended to six years in certain circumstances. Tax returns for open years have incorporated no uncertain tax positions that require a provision for income taxes.

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 or realized capital gain. Reclassifications between income and gain relate primarily to the offset of the current net operating loss against realized gains. For the year ended December 31, 217, the following reclassifications were recorded to reflect tax character (there was no impact on results of operations or net assets):

Distributions during the years ended December 31, 2017 and December 31, 2016, were characterized for tax purposes as follows:

At December 31, 2017, the tax-basis cost of investments, including derivatives, and components of net assets were as follows:

The difference between book-basis and tax-basis net unrealized appreciation (depreciation) is attributable to the deferral of losses from wash sales and the realization of gains/losses on passive foreign investment companies for tax purposes.

The fund is managed by T. Rowe Price Associates, Inc. (Price Associates), a wholly owned subsidiary of T. Rowe Price Group, Inc. (Price Group). The investment management agreement between the fund and Price Associates 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 0.265% for assets in excess of $650 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, 2017, the effective annual group fee rate was 0.29%.

The I Class is subject to an operating expense limitation (I Class limit) pursuant to which Price Associates is contractually required to pay all operating expenses of the I Class, excluding management fees, interest, expenses related to borrowings, taxes, brokerage, and other non-recurring expenses permitted by the investment management agreement, to the extent such operating expenses, on an annualized basis, exceed 0.05% of average net assets. This agreement will continue until April 30, 2018, and may be renewed, revised, or revoked only with approval of the fund’s Board. The I Class is required to repay Price Associates for expenses previously paid to the extent the class’s net assets grow or expenses decline sufficiently to allow repayment without causing the class’s operating expenses (after the repayment is taken into account) to exceed both: (1) the expense limitation in place at the time such amounts were paid; and (2) the class’s current expense limitation. However, no repayment will be made more than three years after the date of a payment or waiver. For the year ended December 31, 2017, I Class operated below its expense limitation.

In addition, the fund has entered into service agreements with Price Associates and two wholly owned subsidiaries of Price Associates (collectively, Price). Price Associates provides certain accounting and 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, R Class and I Class. For the year ended December 31, 2017, expenses incurred pursuant to these service agreements were $86,000 for Price Associates; $3,207,000 for T. Rowe Price Services, Inc.; and $6,963,000 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, 2017, the fund was charged $266,000 for shareholder servicing costs related to the college savings plans, of which $221,000 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, 2017, 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 Spectrum Funds (Spectrum Funds) and T. Rowe Price Retirement Funds (Retirement Funds) may invest. None of the Spectrum Funds or Retirement Funds invest in the underlying Price funds for the purpose of exercising management or control. Pursuant to special servicing agreements, expenses associated with the operation of the Spectrum Funds and 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 Spectrum Funds and Retirement Funds. Expenses allocated under these special servicing agreements are reflected as shareholder servicing expense in the accompanying financial statements. For the year ended December 31, 2017, the fund was allocated $111,000 of Spectrum Funds’ expenses and $7,099,000 of Retirement Funds’ expenses. Of these amounts, $2,643,000 related to services provided by Price. At period-end, the amount payable to Price pursuant to these special servicing agreements is reflected as Due to Affiliates in the accompanying financial statements. At December 31, 2017, approximately 19% of the outstanding shares of the Investor Class were held by the Spectrum Funds and Retirement Funds.

In addition, other mutual funds, trusts, and other accounts managed by Price Associates or its affiliates (collectively, Price funds and accounts) may invest in the fund and are not subject to the special servicing agreements disclosed above. No Price fund or account may invest for the purpose of exercising management or control over the fund. At December 31, 2017, approximately 13% of the I Class’s outstanding shares were held by Price funds and accounts.

The fund may invest its cash reserves in certain open-end management investment companies managed by Price Associates and considered affiliates of the fund: the T. Rowe Price Government Reserve Fund or the T. Rowe Price Treasury Reserve Fund, organized as money market funds, or the T. Rowe Price Short-Term Fund, a short-term bond fund (collectively, the Price Reserve Funds). The Price Reserve Funds are offered as short-term investment options to mutual funds, trusts, and other accounts managed by Price Associates or its affiliates and are not available for direct purchase by members of the public. Cash collateral from securities lending is invested in the T. Rowe Price Short-Term Fund. The Price Reserve Funds pay no investment management fees.

The fund may participate in securities purchase and sale transactions with other funds or accounts advised by Price Associates (cross trades), in accordance with procedures adopted by the fund’s Board and Securities and Exchange Commission rules, which require, among other things, that such purchase and sale cross trades be effected at the independent current market price of the security. During the year ended December 31, 2017, the aggregate value of purchases and sales cross trades with other funds or accounts advised by Price Associates was less than 1% of the fund’s net assets as of December 31, 2017.

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

We have audited the accompanying statement of assets and liabilities, including the portfolio of investments, of T. Rowe Price Mid-Cap Growth Fund, Inc. (the “Fund”) as of December 31, 2017, the related statement of operations for the year ended December 31, 2017, the statement of changes in net assets for each of the two years in the period ended December 31, 2017, including the related notes, and the financial highlights for each of the periods indicated therein (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Fund as of December 31, 2017, 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 ended December 31, 2017 and the financial highlights for each of the periods indicated therein, in conformity with accounting principles generally accepted in the United States of America.

These financial statements are the responsibility of the Fund’s management. Our responsibility is to express an opinion on the Fund’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Fund in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits of these financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. Our procedures included confirmation of securities owned as of December 31, 2017 by correspondence with the custodians, transfer agent and brokers; when replies were not received from brokers, we performed other auditing procedures. We believe that our audits provide a reasonable basis for our opinion.

We have served as the auditor of one or more investment companies in the T. Rowe Price group of investment companies since 1973.

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.

For taxable non-corporate shareholders, $181,247,000 of the fund’s income represents qualified dividend income subject to a long-term capital gains tax rate of not greater than 20%.

For corporate shareholders, $167,790,000 of the fund’s income qualifies for the dividends-received deduction.

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. You may request this document by calling 1-800-225-5132 or by accessing the SEC’s website, sec.gov.

The description of our proxy voting policies and procedures is also available on our corporate website. To access it, please visit the following Web page:

Scroll down to the section near the bottom of the page that says, “Proxy Voting Policies.” Click on the Proxy Voting Policies link in the shaded box.

Each fund’s most recent annual proxy voting record is available on our website and through the SEC’s website. To access it through T. Rowe Price, visit the website location shown above, and scroll down to the section near the bottom of the page that says, “Proxy Voting Records.” Click on the Proxy Voting Records link in the shaded box.

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 website (sec.gov); hard copies may be reviewed and copied at the SEC’s Public Reference Room, 100 F St. N.E., Washington, DC 20549. For more information on the Public Reference Room, call 1-800-SEC-0330.

Your fund is overseen by a Board of Directors (Board) that meets regularly to review a wide variety of matters affecting or potentially affecting the fund, including performance, investment programs, compliance matters, advisory fees and expenses, service providers, and business and regulatory affairs. The Board elects the fund’s officers, who are listed in the final table. At least 75% of the Board’s members are independent of T. Rowe Price Associates, Inc. (T. Rowe Price), and its affiliates; “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 fund directors and is available without charge by calling a T. Rowe Price representative at 1-800-638-5660.

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.

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

(a) – (d) Aggregate fees billed for the last two fiscal years for professional services rendered to, or on behalf of, the registrant 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 $2,169,000 and $2,146,000, respectively.

(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.

(a) 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.

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

(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.

(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.

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 15, 2018


		By	/s/ Catherine D. Mathews
			Catherine D. Mathews
			Principal Financial Officer

Date	February 15, 2018

●	$213,243,000 from short-term capital gains.

●	$2,476,548,000 from long-term capital gains, subject to a long-term capital gains tax rate of not greater than 20%.

Independent Directors

Name
(Year of Birth)
Year Elected*
[Number of T. Rowe Price		Principal Occupation(s) and Directorships of Public Companies and
Portfolios Overseen]		Other Investment Companies During the Past Five Years

Bruce W. Duncan		Chief Executive Officer and Director (2009 to December 2016),
(1951)		Chairman of the Board (January 2016 to present), and President
2013		(2009 to September 2016), First Industrial Realty Trust, an owner
[191]		and operator of industrial properties; Chairman of the Board
		(2005 to September 2016) and Director (1999 to September 2016),
		Starwood Hotels & Resorts, a hotel and leisure company; Director,
		Boston Properties (May 2016 to present); Director, Marriott
		International, Inc. (September 2016 to present)

Robert J. Gerrard, Jr.		Advisory Board Member, Pipeline Crisis/Winning Strategies, a
(1952)		collaborative working to improve opportunities for young African
2012		Americans (1997 to present)
[191]

Paul F. McBride		Advisory Board Member, Vizzia Technologies (2015 to present)
(1956)
2013
[191]

Cecilia E. Rouse, Ph.D.		Dean, Woodrow Wilson School (2012 to present); Professor and
(1963)		Researcher, Princeton University (1992 to present); Member of
2012		National Academy of Education (2010 to present); Director, MDRC,
[191]		a nonprofit education and social policy research organization
		(2011 to present); Research Associate of Labor Studies Program
		(2011 to 2015) and Board Member (2015 to present), National
		Bureau of Economic Research (2011 to present); Chair of Committee
		on the Status of Minority Groups in the Economic Profession
		(2012 to present); Vice President (2015 to present), American
		Economic Association

John G. Schreiber		Owner/President, Centaur Capital Partners, Inc., a real estate
(1946)		investment company (1991 to present); Cofounder, Partner, and
2001		Cochairman of the Investment Committee, Blackstone Real Estate
[191]		Advisors, L.P. (1992 to 2015); Director, General Growth Properties,
		Inc. (2010 to 2013); Director, Blackstone Mortgage Trust, a real
		estate finance company (2012 to 2016); Director and Chairman of
		the Board, Brixmor Property Group, Inc. (2013 to present); Director,
		Hilton Worldwide (2013 to present); Director, Hudson Pacific
		Properties (2014 to 2016)

Mark R. Tercek		President and Chief Executive Officer, The Nature Conservancy
(1957)		(2008 to present)
2009
[191]

*Each independent director 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) and Directorships of Public Companies and
Portfolios Overseen]		Other Investment Companies During the Past Five Years

Edward C. Bernard		Director and Vice President, T. Rowe Price; Vice Chairman of the
(1956)		Board, Director, and Vice President, T. Rowe Price Group, Inc.;
2006		Chairman of the Board, Director, and Vice President, T. Rowe Price
[191]		Investment Services, Inc., and T. Rowe Price Services, Inc.; Chairman
		of the Board and Director, T. Rowe Price Retirement Plan Services,
		Inc.; Chairman of the Board, Chief Executive Officer, Director, and
		President, T. Rowe Price International and T. Rowe Price Trust
		Company; Chairman of the Board, all funds

Robert W. Sharps, CFA, CPA**		Vice President, T. Rowe Price, T. Rowe Price Group, Inc., and T. Rowe
(1971)		Price Trust Company
2017
[135]

*Each inside director serves until retirement, resignation, or election of a successor.
**Effective April 1, 2017, Brian C. Rogers was replaced by Robert W. Sharps as an inside director of certain Price Funds.

Officers

Name (Year of Birth)
Position Held With Mid-Cap Growth Fund		Principal Occupation(s)

Kennard W. Allen (1977)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Brian W.H. Berghuis, CFA (1958)		Vice President, T. Rowe Price, T. Rowe Price
President		Group, Inc., and T. Rowe Price Trust Company

Darrell N. Braman (1963)		Vice President, Price Hong Kong, Price
Vice President and Secretary		Singapore, T. Rowe Price, T. Rowe Price Group,
		Inc., T. Rowe Price International, T. Rowe Price
		Investment Services, Inc., and T. Rowe Price
		Services, Inc.

Shawn T. Driscoll (1975)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company

Donald J. Easley, CFA (1971)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Henry M. Ellenbogen (1973)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company

Joseph B. Fath, CPA (1971)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company

John R. Gilner (1961)		Chief Compliance Officer and Vice President,
Chief Compliance Officer		T. Rowe Price; Vice President, T. Rowe Price
		Group, Inc., and T. Rowe Price Investment
		Services, Inc.

Paul J. Krug, CPA (1964)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company

Robert J. Marcotte (1962)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Catherine D. Mathews (1963)		Vice President, T. Rowe Price, T. Rowe Price
Treasurer and Vice President		Group, Inc., and T. Rowe Price Trust Company

Jason Nogueira, CFA (1974)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

David Oestreicher (1967)		Director, Vice President, and Secretary, T. Rowe
Vice President		Price Investment Services, Inc., T. Rowe Price
		Retirement Plan Services, Inc., T. Rowe
		Price Services, Inc., and T. Rowe Price Trust
		Company; Chief Legal Officer, Vice President,
		and Secretary, T. Rowe Price Group, Inc.; Vice
		President and Secretary, T. Rowe Price and
		T. Rowe Price International; Vice President,
		Price Hong Kong and Price Singapore

Vivek Rajeswaran (1985)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

John W. Ratzesberger (1975)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., and T. Rowe Price Trust Company;
		formerly, North American Head of Listed
		Derivatives Operation, Morgan Stanley
		(to 2013)

Shannon H. Rauser (1987)		Employee, T. Rowe Price
Assistant Secretary

Taymour R. Tamaddon, CFA (1976)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

John F. Wakeman (1962)		Vice President, T. Rowe Price and T. Rowe Price
Executive Vice President		Group, Inc.

Megan Warren (1968)		Vice President, T. Rowe Price, T. Rowe Price
Vice President		Group, Inc., T. Rowe Price Retirement Plan
		Services, Inc., T. Rowe Price Services, Inc.,
		and T. Rowe Price Trust Company; formerly,
		Executive Director, JP Morgan Chase (to 2017)

Justin P. White (1981)		Vice President, T. Rowe Price and T. Rowe Price
Vice President		Group, Inc.

Unless otherwise noted, officers have been employees of T. Rowe Price or T. Rowe Price International for at least 5 years.

/s/ Edward C. Bernard

Edward C. Bernard

Principal Executive Officer

February 15, 2018