UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE

SECURITIES EXCHANGE ACT OF 1934

(AMENDMENT NO.    )

Filed by the Registrantx   Filed by a Party Other Than the Registrant¨

Check the Appropriate Box:

MFS SERIES TRUST I

MFS SERIES TRUST II

MFS SERIES TRUST III

MFS SERIES TRUST IV

MFS SERIES TRUST V

MFS SERIES TRUST VI

MFS SERIES TRUST VIII

MFS SERIES TRUST IX

MFS SERIES TRUST X

MFS SERIES TRUST XI

MFS SERIES TRUST XII

MFS SERIES TRUST XIII

MASSACHUSETTS INVESTORS GROWTH STOCK FUND

MASSACHUSETTS INVESTORS TRUST

(Names of Registrants as Specified in their Charters)

(Name of Person(s) Filing Proxy Statement, if other than the Registrants)

Payment of Filing Fee (Check the Appropriate Box):

500 Boylston Street,

Boston, MA 02116-3741

December 28, 2007

Dear Shareholder:

A Special Meeting of Class R1 shareholders (the “Special Meeting”) of the Funds referenced above (each a “Fund” and collectively the “Funds”) will be held at the offices of the Funds, 500 Boylston Street, 24^th24th Floor, Boston, Massachusetts, on February 15, 2008 at [time]9:30 a.m. Eastern Standard Time.

At this meeting, you are being asked to vote on an important proposal affecting the Class R1 shares of your Fund(s). The Board of Trustees of your Fund(s) believes that this proposal is in the Funds’ and your best interest.

While you are, of course, welcome to join us at the Special Meeting on February 15, 2008, most shareholders vote by telephone, over the Internet, or by filling out, signing, and returning the enclosed proxy card[(s)]card(s).

Your vote makes a difference.    No matter what the size of your investment, your vote is important. The Board of Trustees of the Funds unanimously recommends that you vote in favor of this proposal, but however you decide to vote, it is important that you take the time to do so. By voting early, you can help save your Fund(s) the expense of additional mailings to solicit shareholder votes.

Information regarding the proposal is available in the proxy statement. There are three convenient ways to vote: by telephone, over the Internet, or by filling out, signing and returning the enclosed proxy card[(s)]card(s). Voting instructions are provided on the enclosed proxy card.card(s).

If you have any questions, please contact your investment professional. For questions regarding the proposal, please call the proxy solicitor, Broadridge Financial Solutions, Inc., toll-free at 866-414-6353.866-414-6353, Monday-Friday, 9:30 a.m. to 9:00 p.m. Eastern Standard Time and Saturday, 10:00 a.m. to 6:00 p.m. Eastern Standard Time.

Thank you for your prompt vote.

Sincerely,

500 Boylston Street, Boston, Massachusetts 02116-3741

NOTICE OF A SPECIAL MEETING OF SHAREHOLDERS

TO BE HELD ON FEBRUARY 15, 2008

Notice is hereby given that a Special Meeting of the Class R1 shareholders (the “Special Meeting”) of the Funds referenced above (each a “Fund” and collectively the “Funds”) will be held at the Funds’ offices at 500 Boylston Street, Boston, Massachusetts on Friday, February 15, 2008, at [time]9:30 a.m. Eastern Standard Time, for the following purposes:

THE BOARD OF TRUSTEES UNANIMOUSLY RECOMMENDS

THAT YOU CAST YOUR VOTE “FOR” PROPOSAL 1.

This is a notice and proxy statement for your Fund’s shareholder meeting. Each Fund’s Class R1 shareholders of record as of the close of business on December 10, 2007 will be entitled to notice of, and to vote at, the Special Meeting and any adjournments thereof only on those matters being considered for their Fund. [IfIf you own Class R1 shares of more than one of the Funds, each of your Funds is listed on the enclosedseparate proxy voting card.]cards are included for each Fund in which you own Class R1 shares. Please complete, sign and return the enclosed proxy voting card[(s)]card(s).

Your attention is directed to the attached proxy statement.

By order of the Board of Trustees

Susan S. Newton

Assistant Secretary and Assistant Clerk

December 28, 2007

YOUR VOTE IS IMPORTANT. WE WOULD APPRECIATE YOU PROMPTLY VOTING, SIGNING AND RETURNING THE ENCLOSED PROXY CARD[(S)]CARD(S) SO THAT IT IS RECEIVED BY THE DATE OF THE SPECIAL MEETING, OR RECORDING YOUR VOTING INSTRUCTIONS BY TELEPHONE OR VIA THE INTERNET BY [time]9:29 a.m. EASTERN STANDARD TIME, ON THE DATE OF THE SPECIAL MEETING, WHICH WILL HELP AVOID THE ADDITIONAL EXPENSE OF A SECOND SOLICITATION FOR YOUR FUND. THE ENCLOSED ADDRESSED ENVELOPE REQUIRES NO POSTAGE AND IS PROVIDED FOR YOUR CONVENIENCE.

PROXY STATEMENTProxy Statement

500 Boylston Street

Boston, Massachusetts 02116-3741

Special Meeting of Shareholders

To be held February 15, 2008

This Proxy Statement is furnished to the Class R1 shareholders of each Fund referenced above (each a “Fund” and collectively the “Funds”) in connection with the solicitation of proxies by and on behalf of the Board of Trustees (the “Trustees”) of each registered investment company set forth above (the “Trusts”) to be used at the Special Meeting of Shareholders (the “Special Meeting”) to be held at 9:30 a.m., Eastern Standard Time

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on February 15, 2008 at 500 Boylston Street, 24^th24th floor, Boston, Massachusetts 02116, for the purposes set forth in the accompanying Notice of a Special Meeting of Shareholders (the “Notice”). IfProxies, including proxies given by telephone or via the enclosed form of proxy is executed and returned, it neverthelessInternet, may be revoked at any time before it isthey are voted by (i) a written revocation received by the Secretary of the applicable Fund,Fund; (ii) by properly executing a later-dated proxy,proxy; or (iii) by attending the Special Meeting and voting in person. Solicitation of proxies is being made by the mailing of the Notice and this Proxy Statement with its enclosures on or about December 28, 2007.

The Special Meeting is being called in order to ask Class R1 shareholders of the Funds to consider and vote on the following proposals:

Shareholders of record of each Fund at the close of business on December 10, 2007 will be entitled to one vote for each dollar of net asset value held on that date (i.e., the number of shares owned times the net asset value per share) (the “Record Holders”). Each fractional dollar amount is entitled to a proportionate fractional vote.

Shareholders have the opportunity to submit their voting instructions via the Internet by using a program provided by aBroadridge Financial Solutions, Inc. (a third-party vendor retained by the Funds,Funds), by automated telephone service or by mail using the enclosed proxy card[(s)]card(s). Internet and telephone voting is available until 9:29 a.m., Eastern Standard Time, on February 15, 2008.

The mailing address of the Trusts and of each of the Funds is 500 Boylston Street, Boston, Massachusetts 02116.

A copy of each Fund’s most recent annual report and semi-annual report may be obtained without charge by contacting MFS Service Center, Inc., the Funds’ transfer and shareholder servicing agent, at 500 Boylston Street, Boston, Massachusetts 02116, or by telephoning toll-free (800) 225-2606.

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Proposal 1:

To Approve an Amendment ofto the Current Master Distribution Plan Adopted Pursuant to Rule 12b-1 under the Investment Company Act of 1940, as amended, with Respect to Class R1 Shares of Your Fund(s)

Introduction

Class R1 Shares of each Fund are sold to retirement plans at their net asset value without an initial sales charge. Class R1 Shares have generally been available to retirement plans only if MFS or an affiliate of MFS is either responsible for providing participant recordkeeping services or has entered into an administrative arrangement with a third party to provide certain recordkeeping and/or administrative services. As of January 1, 2008, Class R1 shares will be available to other retirement plans where MFS or an affiliate is not providing participant recordkeeping services or has not entered into an administrative arrangement with a third party to provide recordkeeping or administrative services.

Each Fund has adopted a distribution plan in accordance with Rule 12b-1 under the Investment Company Act of 1940, as amended (the “Distribution Plan”). Under the Distribution Plan, each Fund pays distribution and/or service fees to MFS Fund Distributors, Inc. (“MFD”), the principal underwriter of each Fund, to support the sale and distribution of shares as well as shareholder servicing and account maintenance activities (“12b-1 Fees”). With respect to Class R1 Shares, these distribution and service fees

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equal on an annual basis up to 0.75% of the average daily net assets attributable to Class R1 Shares, of which 0.50% is a distribution fee and 0.25% is a service fee.

In addition, Massachusetts Financial Services Company (“MFS”), each Fund’s investment adviser and administrator, provides, either directly or through affiliated and/or unaffiliated entities, certain administrative, recordkeeping, and communication/educational services to the retirement plans and retirement plan participants that invest in Class R1 Shares under a Master Class R Administration and Services Agreement (the “Class R Administration and Services Agreement”). Under the Class R Administration and Services Agreement, Class R1 Shares pay an annual fee of 0.35% of the average daily net assets attributable to Class R1 Shares to MFS for these services (the “Class R1 Administrative Services Fee”).

MFS is proposing to amend each Fund’s Distribution Plan to increase the Class R1 12b-1 Fee from 0.75% to 1.00% of the average daily net assets attributable to Class R1 Shares, an increase of 0.25%. If Proposal 1 is approved by Class R1 shareholders of all of the Funds, MFS will eliminate the 0.35% Class R1 Administrative Services Fee, resulting in a 0.10% reduction in the total expense ratio of Class R1 Shares of each Fund. If Proposal 1 is not approved by shareholders ofall of the Funds, the Proposal will not be implemented and the Class R1 12b-1 Fee and the Class R1 Administrative Services Fee will remain unchanged for all Funds. The Proposal is discussed in further detail below under “Proposed Changes to the Current Distribution Plan.”

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General Information about the Current Distribution Plan

The Distribution Plan was adopted on January 1, 1997, and was amended on April 26, 2005, January 24, 2006, April 25, 2006, and October 25, 2006. Under the Distribution Plan, each Fund pays distribution and/or service fees to MFD to support the sale and distribution of Class R1 Shares, as well as shareholder servicing and account maintenance activities. These distribution and service fees equal on an annual basis up to 0.75% of the average daily net assets attributable to Class R1 Shares, of which 0.50% is a distribution fee and 0.25% is a service fee. The Distribution Plan is designed to promote sales of shares of the Funds and minimize redemptions, as well as to assist in the servicing and maintenance of shareholder accounts.

Distribution fees compensate MFD and/or financial intermediaries for their expenses in connection with the distribution of Fund shares, including, but not limited to, commissions to financial intermediaries, printing prospectuses and reports used for sales purposes, the preparation and printing of sales literature, personnel, travel, office expense and equipment, payments made to wholesalers employed by MFD (employees may receive additional compensation if they meet certain targets for sales of one or more MFS Funds), and other distribution-related expenses.

Service fees compensate MFD and/or financial intermediaries for shareholder servicing and account maintenance activities, including, but not limited to, shareholder recordkeeping (including assisting in establishing and maintaining customer accounts and records), transaction processing (including assisting with purchase, redemption and exchange requests), shareholder reporting, arranging for bank wires, monitoring dividend payments from the Funds on behalf of customers, forwarding certain shareholder communications from the Funds to customers, corresponding with shareholders and customers regarding the Funds (including receiving and responding to inquiries and answering questions regarding the Funds), and aiding in maintaining the investment of their respective customers in the Funds.

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The Distribution Plan remains in effect from year to year only if its continuance is specifically approved at least annually by a vote of the Trustees, including a majority of the Trustees who are not “interested persons” of the Funds (the “independent Trustees”). The Distribution Plan for each Fund was most recently approved by the Board of Trustees in July 2007.

Proposed Changes to the Current Distribution Plan

Proposal 1 would amend the Funds’ Distribution Plan to increase the 12b-1 Fees payable under the Distribution Plan with respect to Class R1 Shares from 0.75% to 1.00% of the average daily net assets attributable to a Fund’s Class R1 Shares, an increase of 0.25%. If Proposal 1 is approved by Class R1 shareholders of all of the Funds, MFS will eliminate the Class R1 Administrative Services Fee of 0.35% for each Fund and terminate the Class R Administration and Services Agreement. As a result, the total expense ratio of Class R1 Shares of each Fund will decrease by 0.10%. The additional 0.25% of 12b-1 Fees will generally be used by MFD to compensate recordkeepers, who are currently receiving the Class R1 Administrative Services Fee of 0.35%, and MFD does not intend to retain any amounts attributable to the increase in the Class R1 12b-1 Fee.

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The amendment to the Distribution Plan to increase the Class R1 12b-1 Fee and the corresponding elimination of the Class R1 AdministrationAdministrative Services Fee will only be implemented if Proposal 1 is approved by Class R1 shareholders of all of the Funds. If approved, the amendment to the Distribution Plan and the corresponding elimination of the Class R1 Administrative Services Fee will be effective March 1, 2008 (or such later date as authorized by the Trustees of the Funds). If Proposal 1 is not approved by the Class R1 shareholders ofall of the Funds, the Proposal will not be implemented and the Class R1 12b-1 Fee and the Class R1 Administrative Services Fee will remain unchanged for all of the Funds.

MFS believes that Proposal 1 is in the best interests of shareholders, as the total expense ratio of Class R1 Shares of each Fund will decrease by 0.10% if Proposal 1 is approved and implemented as described above. In addition, MFS believes that the increase in the Class R1 12b-1 Fee and the corresponding elimination of the Class R1 Administrative Services Fee may stimulate additional sales of Class R1 Shares of the Funds, thus increasing Fund assets. MFS believes that the proposed change to the fee structure competitively compensates financial intermediaries and recordkeepers for their services to Class R1 Shares of the Funds, and, at the same time, allows Class R1 shareholders to realize reductions in total expenses for their Class R1 Shares.

A comparison of the current fees and the proposed fees with respect to Class R1 Shares of each Fund is provided inSchedule I: Actual and Pro Forma Fund Expenses.

The amount of fees and expenses paid by Class R1 Shares for each Fund under the current Distribution Plan during each Fund’s most recently reported fiscal year, both in the aggregate and as a percentage of the Class’Funds’ average daily net asset value, is shown inSchedule IIattached hereto.

Consideration and Recommendation by Trustees

The Trustees reviewed this Proposal and after consideration and consultation with legal counsel unanimously approved the amendment to the Distribution Plan and authorized the Trusts to seek shareholder approval to amend the Distribution Plan as set forth in the Proposal. The Trustees believe that there is a reasonable likelihood that the proposed fee increase under the Distribution Plan and corresponding

4

elimination of the Class R1 Administrative Services Fee will benefit each Fund’s Class R1 shareholders and each Fund.its shareholders. The Trustees considered numerous factors, including:

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In addition, the Trustees considered the possible benefits that may be realized by MFS and MFD as a result of the adoption of the amendments to the Distribution Plan, including the possibility that management fees, administrative fees and shareholder servicing fees paid to MFS and MFD would increase with an increase in the size of the Funds.

Based on these and other factors, each Fund’s Board of Trustees voted to approve such proposed amendment to the Distribution Plan and concluded that the proposed amendment would be in the best interests of each Fund and the shareholders of each Fund’s Class R1 Shares.and its shareholders. The Trustees’ approval included a determination that, in the exercise of reasonable business judgment and in light of their fiduciary duties under applicable laws, there is a reasonable likelihood that the amendment to the Distribution Plan will benefit each of the Funds and each Fund’s Class R1 and its shareholders.

If approved by Class R1 shareholders of all of the Funds, the amendment to the Distribution Plan will be effective March 1, 2008 (or such later date as authorized by the Trustees of the Funds) and will continue in effect for up to one year, and then from year to year so long as it is approved by a majority of the Board of Trustees, including a majority of the independent Trustees. The current Distribution Plan provides that it may not be amended to increase materially the amount of the 12b-1 Fee payable under the Distribution Plan unless the increase is approved by the Class R1 shareholders, voting separately, of the respective Fund. Under current regulatory requirements, the 12b-1 Fee cannot be increased above 1.00% of the average daily net assets of the Class. The Distribution Plan will terminate automatically in the event of its assignment and may be terminated at any time upon a vote of a majority of the independent Trustees who have no direct or indirect financial interest in the operation of the Distribution Plan, or by vote of a majority of the outstanding Class R1 Shares of a Fund.

Required Vote

Approval of this matter will require the vote of the lesser of (i) 67% or more of the outstanding voting securities of the Class R1 Shares of a Fund present at the Special Meeting, if the holders of more than 50% of the outstanding voting securities of the Class R1 Shares of the Fund are present in person or represented by proxy at the Special Meeting or (ii) more than 50% of the outstanding voting securities of the Class R1 Shares of a Fund.

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Proposal 1 will only be implemented if it is approved by Class R1 shareholders ofall of the Funds. If Proposal 1 is not approved by Class R1 shareholders ofall of the Funds, the Proposal will not be implemented and the Class R1 12b-1 Fee and the Class R1 Administrative Services Fee will remain unchanged for all of the Funds.

The Trustees of each Fund unanimously recommend that you vote FOR Proposal 1.

Fund InformationFUND INFORMATION

This section provides certain information about each Fund, including information about its investment adviser, principal underwriter and administrator, and the identity of persons holding of record or beneficially 5% or more of the outstanding Class R1 Shares of a Fund.

Investment Adviser, Principal Underwriter Andand Administrator

Each Fund’s investment adviser and administrator is MFS, a Delaware corporation with offices at 500 Boylston Street, Boston, Massachusetts 02116. The Funds’ principal underwriter is MFD, a Delaware corporation with offices at 500 Boylston Street, Boston, Massachusetts 02116. MFS is a majority owned-owned subsidiary of Sun Life of Canada (U.S.) Financial Services Holdings, Inc., which in turn is a majority-owned subsidiary of Sun Life Financial (U.S.) Holdings, Inc., which has an address of 500 Boylston Street, Boston, Massachusetts 02116. Sun Life Financial (U.S.) Holdings, Inc. is a wholly-owned subsidiary of Sun Life Assurance Company of Canada-U.S. Operations Holdings, Inc., One Sun Life Executive Park, Wellesley Hills, Massachusetts 02481 (“Sun Life U.S. Operations”). Sun Life U.S. Operations is a wholly-owned subsidiary of Sun Life Financial Corp., which has an address of 150 King Street West, Toronto, Canada MSH 1J9, and which is a wholly-owned subsidiary of Sun Life Financial Inc.

Interests of Certain Persons

Schedule IV attached hereto sets forth, to the best knowledge of each Fund, the shareholders who owned of record or beneficially 5% or more of a Fund’s outstanding Class R1 Shares as of the close of business on December 3, 2007.

[As of December 3, 2007, the officers and directors of the Funds, as a group, owned less than 1% of each Fund’s outstanding Class R1 Shares.]

Further Information about Voting and the Special MeetingFURTHER INFORMATION ABOUT VOTING AND THE SPECIAL MEETING

Outstanding Shares, Method of Tabulation and Quorum

Schedule III attached hereto sets forth, as of the close of business as of December 10, 2007, the total number of Class R1 Shares that were issued and outstanding for each Fund. Shareholders of record at the close of business on December 10, 2007 will be entitled to one vote for each dollar of net asset value held on that date (i.e., the number of shares owned times the net asset value per share), with fractional amounts voting

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proportionately. Shares representing a majority of the voting power of the outstanding Class R1 Shares of a Fund entitled to be cast at the Special Meeting that are present in person or represented by proxy constitute a quorum with respect to that Fund.

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Manner of Voting Proxies

All proxies received by management will be voted on all matters presented at the Special Meeting, and if not limited to the contrary, will be voted FOR the Proposal to amend each Fund’s Distribution Plan. All proxies received, including proxies that reflect (i) broker non-votes (i.e., shares held by brokers or nominees as to which (a) instructions have not been received from the beneficial owners or the persons entitled to vote, and (b) the broker or nominee does not have discretionary voting power on a particular matter), (ii) abstentions or (iii) the withholding of authority to vote, will be counted as shares that are present on a particular matter for purposes of determining the presence of a quorum for that matter. Broker non-votes, abstentions and withholding authority to vote will all have the effect of a vote AGAINST the Proposal.

Each Fund will reimburse the Record Holders for their expenses incurred in sending proxy materials to, and obtaining voting instructions from, beneficial owners.

Solicitation of Proxies

In addition to soliciting proxies by mail, the Trustees of your Funds and employees of MFS, MFS Fund Distributors, Inc., and MFS Service Center, Inc. may solicit proxies in person or by telephone. In addition, the Funds have retained, at their own expense, Broadridge Financial Solutions, Inc., 60 Research Road, Hingham, Massachusetts 02043, to aid in the solicitation of instructions for nominee and registered accounts for a fee of approximately $12,000 in the aggregate, plus reasonable out-of-pocket expenses for proxy solicitation services, which will be paid on a proportionate basis by the Funds.

The Funds may also arrange to have votes recorded by telephone. The telephonic voting procedure is designed to authenticate shareholders’ identities, to allow shareholders to authorize the voting of their shares in accordance with their instructions and to confirm that their instructions have been properly recorded. Shareholders would be asked for their Social Security numbers or other identifying information. The shareholders would then be given an opportunity to authorize their proxies to vote their shares at the Special Meeting in accordance with their instructions. To ensure that the shareholders’ instructions have been recorded correctly, they will also receive a confirmation of their instructions in the mail. A toll-free number will be available in the event the information contained in the confirmation is incorrect.

Shareholders also have the opportunity to submit their voting instructions via the Internet as directed on your proxy card[(s)]card(s). The giving of such a proxy will not affect your right to vote in person should you decide to attend the Special Meeting. To use the Internet, you will need the “control” number that appears on your proxy card[(s)]card(s). The Internet voting procedures, which are included on the Internet address on your proxy card[(s)]card(s), are designed to authenticate shareholder identities, to allow shareholders to give their voting instructions, and to confirm that shareholders’ instructions have been recorded properly.

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Instructions for Voting Proxies

The giving of a proxy will not affect a shareholder’s right to vote in person should the shareholder decide to attend the Special Meeting. To vote by mail, please mark, sign, date and return the enclosed proxy card[(s)]card(s) following the instructions printed on the card[(s)]card(s). To use the Internet, please access the Internet address listed on your proxy card[(s)]card(s) and follow the instructions on the website. Shareholders voting via the Internet should understand that there may be costs associated with electronic access, such as usage charges from Internet access providers and telephone companies, that must be borne by the shareholders. To record your voting instructions via automated telephone service, please call the toll-free number listed on the enclosed proxy card[(s)]card(s).

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Revocation of Proxies

Proxies, including proxies given by telephone or via the Internet, may be revoked at any time before they are voted either (i) by a written revocation received by the Secretary of the applicable Fund, (ii) by properly executing a later-dated proxy, or (iii) by attending the Special Meeting and voting in person.

Adjournment

With respect to each Fund, if the necessary quorum to transact business or sufficient votes in favor of the Proposal are not received by the time scheduled for the Special Meeting, the persons named as proxies may propose adjournments of the Special Meeting to permit further solicitation of proxies with respect to the Fund. Any adjournment will require the affirmative vote of a majority of the votes cast on the question in person or by proxy at the session of the Special Meeting to be adjourned. The persons named as proxies will vote in favor of such adjournment those proxies which they are entitled to vote in favor of the proposal. They will vote against any such adjournment those proxies required to be voted against the proposal. They will not vote any proxy that directs them to abstain from voting on the proposal. The applicable Funds will pay the costs of any additional solicitation and of any adjourned session.

Submission of Proposals

Each Fund is a (or is part of aa) Massachusetts business trust, and as such is not required to hold annual meetings of shareholders. However, the Trustees may from time to time schedule special meetings. Shareholder proposals for inclusion in a Fund’s proxy statement for any subsequent meeting must be received by the applicable Fund a reasonable period of time prior to any such meeting.

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Cost of Proxy Solicitation

The expense of the preparation, printing and mailing of the enclosed form of proxy, the Notice, and this Proxy Statement, and any tabulation costs, will be borne on a proportional basis by the Funds.

Other Business

Each Fund knows of no other matters to be brought before the Special Meeting. If, however, because of any unexpected occurrence, any matters properly come before the Special Meeting, it is a Fund’s intention that proxies not limited to the contrary will be voted in accordance with the judgment of the persons named in the enclosed formform(s) of proxy.

Additional Information

The Special Meeting of shareholders of your Fund is called to be held at the same time as the meetings of shareholders of certain of the other Funds. It is anticipated that all Special Meetings will be held simultaneously. If any shareholder at the Special Meeting objects to the holding of simultaneous Special Meetings and moves for an adjournment of that Special Meeting to a time promptly after the simultaneous Special Meetings, the persons named as proxies will vote in favor of such adjournment.

Only one copy of this Proxy Statement may be mailed to a Record Holder’s household, even if more than one person in a household is a Record Holder, unless the Fund has received contrary instructions from one or more of the shareholders. If you need additional copies of this Proxy Statement and you are the Record Holder of your shares, please contact MFS Service Center, Inc. at 1-800-637-2304.1-800-225-2606. If your shares are held in broker street name, please contact your financial intermediary to obtain additional copies of this proxy statement.Proxy Statement. If in the future you do not want the mailing of proxy statements to be

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combined with those for other members of your household, or if, within your household, you are receiving multiple copies of this Proxy Statement and want the mailings to be combined with those for other members of your household, contact MFS Service Center, Inc in writing at 500 Boylston Street, Boston, Massachusetts 02116, or by telephone at 1-800-637-2304,1-800-225-2606, or contact your financial intermediary.

IT IS IMPORTANT THAT PROXIES BE RETURNED PROMPTLY

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Schedule II::

Actual and Pro Forma Fund Expenses

MFS Aggressive Growth Allocation Fund (as of fiscal year ended May 31, 2007)

The Fund is a Fund-of-Funds. The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. In addition to the fees and expenses which you bear directly, you will indirectly bear the Fund’s pro rata share of the fees and expenses of the underlying funds in which the fund invests. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements, and a weighted average of the total annual operating expenses (as reported in each underlying fund’s most recent shareholder report) of, and the fee (if any) charged by (if any), the underlying funds in which the Fund invested during the Fund’s most recently completed fiscal year. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the Class R1 annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-1

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Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is October 1, 2007, the date of the Fund’s current prospectus.

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MFS Bond Fund (as of fiscal year ended April 30, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-3

Example

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The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same, except that the Fund’s total operating expenses are assumed to be the Fund’s “Net Expenses” for the period during which any written fee reductions are in effect (see the Expense Table above). The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is September 1, 2007, the date of the Fund’s current prospectus.

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MFS Cash Reserve Fund (as of fiscal year ended August 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-5

Example

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The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same, except that the Fund’s total operating expenses are assumed to be the Fund’s “Net Expenses” for the period during which any written fee reductions are in effect (see the Expense Table above). The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is January 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

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MFS Conservative Allocation Fund (as of fiscal year ended May 31, 2007)

The Fund is a Fund-of-Funds. The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. In addition to the fees and expenses which you bear directly, you will indirectly bear the Fund’s pro rata share of the fees and expenses of the underlying funds in which the Fund invests. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements, and a weighted average of the total annual operating expenses (as reported in each underlying fund’s most recent shareholder report) of, and the fee (if any) charged by (if any), the underlying funds in which the Fund invested during the Fund’s most recently completed fiscal year. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the Class R1 annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-7

- 17 -

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is October 1, 2007, the date of the Fund’s current prospectus.

- 18 -I-8

MFS Core Equity Fund (as of fiscal year ended August 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-9

- 19 -

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee is has been eliminated. The commencement date for the examplesexample is January 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

- 20 -I-10

MFS Core Growth Fund (as of fiscal year ended August 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-11

- 21 -

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same, except that the Fund’s total operating expenses are assumed to be the Fund’s “Net Expenses” for the period during which any written fee reductions are in effect (see the Expense Table above). The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is January 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

- 22 -I-12

MFS Emerging Growth Fund (as of fiscal year ended November 31, 2006)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently reported fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-13

Example

- 23 -

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same, except that the Fund’s total operating expenses are assumed to be the Fund’s “Net Expenses” for the period during which any written fee reductions are in effect (see the Expense Table above). The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is April 1, 2007, the date of the Fund’s current prospectus.

- 24 -I-14

MFS Global Equity Fund (as of fiscal year ended October 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-15

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s

- 25 -

operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is March 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

- 26 -I-16

MFS Global Growth Fund (as of fiscal year ended October 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

The expenses below assume that you invested $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s

- 27 -

operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examples is March 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

- 28 -

MFS Global Total Return Fund (as of fiscal year ended October 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses are adjusted to give effect to the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

I-17

Example

The expenses below assume that you invest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the example is March 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

I-18

MFS Global Total Return Fund (as of fiscal year ended October 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold Class R1 shares of the Fund. The “Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The “Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-19

- 29 -

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same, except that the Fund’s total operating expenses are assumed to be the Fund’s “Net Expenses” for the period during which any written fee reductions are in effect (see the Expense Table above). The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is March 1, 2008, the date of the Fund’s prospectus following the Fund’s most recent fiscal year end.

- 30 -I-20

MFS Government Securities Fund (as of fiscal year ended February 28, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-21

- 31 -

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same, except that the Fund’s total operating expenses are assumed to be the Fund’s “Net Expenses” for the period during which any written fee reductions are in effect (see the Expense Table above). The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is July 1, 2007, the date of the Fund’s current prospectus.

- 32 -I-22

MFS Growth Allocation Fund (as of fiscal year ended May 31, 2007)

The Fund is a Fund-of-Funds. The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. In addition to the fees and expenses which you bear directly, you will indirectly bear the Fund’s pro rata share of the fees and expenses of the underlying funds in which the fund invests. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements, and a weighted average of the total annual operating expenses (as reported in each underlying fund’s most recent shareholder report) of, and the fee (if any) charged by (if any), the underlying funds in which the Fund invested during the Fund’s most recently completed fiscal year. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the Class R1 annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses

(Expenses that are Deducted from Fund Assets)

I-23

- 33 -

Example

The expenses below assume that you investedinvest $10,000 in Class R1 shares of the Fund for the time periods indicated, you redeem your shares at the end of the time periods, and your investment has a 5% return each year and dividends and other distributions are reinvested and the Fund’s operating expenses remain the same. The Class R1 pro forma expense examples also assume, during the entirety of the time period indicated, that the proposed distribution and service (12b-1) fee under the amended Distribution Plan is in effect and that the annual retirement plan administration and services fee has been eliminated. The commencement date for the examplesexample is October 1, 2007, the date of the Fund’s current prospectus.

- 34 -I-24

MFS High Income Fund (as of fiscal year ended January 31, 2007)

The following tables describe the fees and expenses that you may pay when you buy, redeem, and hold shares of Class R1 shares of the Fund. The actual annual fund operating expenses“Class R1 Actual Expenses” are based on expenses incurred during the Fund’s most recently completed fiscal year adjusted to reflect annualized expenses and current fee arrangements. The pro forma annual fund operating expenses“Class R1 Pro Forma Expenses” are adjusted to give effect to the increase in the Class R1 Distribution and Service (12b-1) Fee, as contemplated under the proposed amendment to the Distribution Plan and the elimination of the annual retirement plan administration and services fee. The Fund’s annual operating expenses may vary in future years.

Annual Fund Operating Expenses