otc.htm

Before you invest, you may want to review the fund’s prospectus, which contains more information about the fund and its risks. You can find the fund’s prospectus and other information about the fund, including the fund’s statement of additional information, online at funds.mfs.com. You can also get this information at no cost by calling 1-800-225-2606 or by sending an e-mail request to orderliterature@mfs.com. The fund’s prospectus and statement of additional information, both dated December 29, 2011, as may be supplemented from time to time, are incorporated by reference into this Summary Prospectus.

CLASS	TICKER SYMBOL
Class A	OTCAX
Class B	OTCBX
Class C	OTCCX
Class I	OTCIX
Class 529A	EAMCX
Class 529B	EBCGX
Class 529C	ECGRX
Class R1	OTCGX
Class R2	MCPRX
Class R3	OTCHX
Class R4	OTCJX

You may qualify for sales charge reductions if you and certain members of your family invest, or agree to invest in the future, at least $50,000 in MFS Funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers or Reductions” on page 7 of the fund’s prospectus and “Waivers of Sales Charges” on page I-14 of the fund’s statement of additional information Part I.

Share Class	A	529A	B AND 529B	C AND 529C	I	ALL R
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	5.75%	5.75%	None	None	None	None
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less)	1.00%#	None	4.00%	1.00%	None	None

Share Class	A	B	C	I	529A	529B	529C	R1	R2	R3	R4
Management Fee	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%
Distribution and/or Service (12b-1) Fees	0.25%	1.00%	1.00%	None	0.25%	1.00%	1.00%	1.00%	0.50%	0.25%	None
Other Expenses	0.28%	0.28%	0.28%	0.28%	0.38%	0.38%	0.38%	0.28%	0.28%	0.28%	0.28%
Total Annual Fund Operating Expenses	1.28%	2.03%	2.03%	1.03%	1.38%	2.13%	2.13%	2.03%	1.53%	1.28%	1.03%
Fee Reductions and/or Expense Reimbursements1	(0.00)%	(0.00)%	(0.00)%	(0.00)%	(0.05)%	(0.05)%	(0.05)%	(0.00)%	(0.00)%	(0.00)%	(0.00)%
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements	1.28%	2.03%	2.03%	1.03%	1.33%	2.08%	2.08%	2.03%	1.53%	1.28%	1.03%

#	On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012.

The fund's distributor, MFS Fund Distributors, Inc. ("MFD"), has agreed in writing to waive the program management fee for each of the fund's Class 529A, Class 529B, and Class 529C shares to 0.05% of the fund's average daily net assets attributable to each share class annually. This written agreement will expire on December 31, 2012, unless MFD elects to extend the waiver.

The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund’s operating expenses remain the same.

	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Class A Shares	$698	$958	$1,237	$2,031
Class B Shares assuming
redemption at end of period	$606	$937	$1,293	$2,166
no redemption at end of period	$206	$637	$1,093	$2,166
Class C Shares assuming
redemption at end of period	$306	$637	$1,093	$2,358
no redemption at end of period	$206	$637	$1,093	$2,358
Class I Shares	$105	$328	$569	$1,259
Class 529A Shares	$703	$982	$1,282	$2,133
Class 529B Shares assuming
redemption at end of period	$611	$962	$1,340	$2,267
no redemption at end of period	$211	$662	$1,140	$2,267
Class 529C Shares assuming
redemption at end of period	$311	$662	$1,140	$2,458
no redemption at end of period	$211	$662	$1,140	$2,458
Class R1 Shares	$206	$637	$1,093	$2,358
Class R2 Shares	$156	$483	$834	$1,824
Class R3 Shares	$130	$406	$702	$1,545
Class R4 Shares	$105	$328	$569	$1,259

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 86% of the average value of its portfolio.

MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in issuers with medium market capitalizations. MFS generally defines medium market capitalization issuers as issuers with market capitalizations similar to market capitalizations of issuers included in the Russell Midcap® Growth Index over the last 13 months at the time of purchase. As of November 30, 2011, the range of the Russell Midcap® Growth Index was between $107.3 million and $19.3 billion.

MFS normally invests the fund’s assets primarily in equity securities. Equity securities include common stocks, preferred stocks, securities convertible into stocks, and depositary receipts for those securities.

MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers. Quantitative models that systematically evaluate issuers may also be considered.

As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

Stock Market/Company Risk: Stock markets are volatile and can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, and other conditions, as well as to investor perceptions of these conditions. The price of an equity security can decrease significantly in response to these conditions, and these conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the market in general.

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, political, regulatory, geopolitical, or other conditions. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Investment Selection Risk: The MFS analysis of an investment can be incorrect and can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests.

Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability to perform in accordance with the terms of the transaction.

The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund’s performance over time compares with that of a broad measure of market performance.

The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com or by calling 1-800-225-2606.

Class A Bar Chart. The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown.

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MFS Mid Cap Growth Fund

The total return for the nine-month period ended September 30, 2011 was (12.68)%. During the period(s) shown in the bar chart, the highest quarterly return was 26.56% (for the calendar quarter ended December 31, 2001) and the lowest quarterly return was (34.81)% (for the calendar quarter ended December 31, 2008).

Share Class	1 YEAR	5 YEARS	10 YEARS
Returns Before Taxes
B Shares	23.63%	(1.22)%	(4.36)%
C Shares	26.66%	(0.81)%	(4.52)%
I Shares	28.94%	0.17%	(3.55)%
529A Shares	21.16%	(1.48)%	(4.63)%
529B Shares	23.60%	(1.37)%	(4.58)%
529C Shares	26.58%	(0.97)%	(4.70)%
R1 Shares	27.57%	(0.87)%	(4.64)%
R2 Shares	28.24%	(0.40)%	(4.16)%
R3 Shares	28.67%	(0.13)%	(3.89)%
R4 Shares	28.91%	0.09%	(3.64)%
A Shares	21.29%	(1.24)%	(4.36)%
Returns After Taxes on Distributions A Shares	21.29%	(1.24)%	(4.42)%
Returns After Taxes on Distributions and Sale of Fund Shares A Shares	13.84%	(1.05)%	(3.62)%
Index Comparison (Reflects no deduction for fees, expenses or taxes)
Russell Midcap Growth Index	26.38%	4.88%	3.12%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown.

You may purchase and redeem shares of the fund each day the New York Stock Exchange is open for trading. You may purchase or redeem shares either by having your financial intermediary process your purchase or redemption, or by overnight mail (MFS Service Center, Inc. (MFSC), c/o Boston Financial Data Services, 30 Dan Road, Canton, MA 02021-2809), by mail ([Fund Name], P.O. Box 55824, Boston, MA 02205-5824), by telephone (1-800-225-2606), or via the Internet at mfs.com (MFS Access).

Class	Initial Minimum	Subsequent Minimum
Class A, Class B, Class C	None – automatic investment plans and certain asset-based fee programs $25 – employer-sponsored retirement plans $250 – Traditional and Roth IRAs $1,000 – other accounts	$50 – by check and non-systematic written exchange request, and via MFSC telephone representatives None – other purchases
Class I, Class R1, Class R2, Class R3, Class R4	None	None
Class 529A, Class 529B, Class 529C	$250	None

If you purchase shares of the fund through a broker/dealer or other financial intermediary (such as a bank), the fund, MFS, and MFS’ affiliates may pay the financial intermediary for the sale of shares of a fund and/or the servicing of shareholder accounts. These payments may create a conflict of interest by influencing your broker/dealer or other financial intermediary and your salesperson to recommend the fund over another investment. Ask your financial intermediary or visit your financial intermediary’s Web site for more information.

Portfolio Manager	Since	Title
Eric B. Fischman	2008	Investment Officer of MFS
Paul J. Gordon	May 2011	Investment Officer of MFS