485BPOS
2012-10-26
0001330967
2012-10-29
MFS Series Trust XII
false
2012-10-26
2012-11-01
<tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate may<br />indicate higher transaction costs and may result in higher taxes when shares are<br />held in a taxable account. These transaction costs, which are not reflected in<br />"Annual Fund Operating Expenses" or in the "Example," affect the fund's<br />performance.</tt>
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<tt>The fund's investment objective is to seek a high level of total return<br />consistent with its asset allocation until the approximate retirement <br />year in the fund's name; thereafter, the fund will seek total return <br />through a combination of current income and capital appreciation. The <br />asset allocation of the fund will change over time.</tt>
<tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods (unless<br />otherwise indicated); your investment has a 5% return each year; and the fund's<br />operating expenses remain the same.</tt>
<tt>The fund is designed to provide diversification among different asset classes<br />for investors with the approximate retirement date in the fund's name. The fund<br />invests substantially all of its assets in other MFS mutual funds, referred to<br />as underlying funds. The underlying funds are selected following a two-stage<br />asset allocation process. The first stage is a strategic asset allocation to<br />establish the percentage of the fund's assets to be invested in the general<br />asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as<br />well as an allocation to underlying funds that have less traditional investment<br />strategies that MFS (Massachusetts Financial Services Company, the fund's<br />investment adviser) believes provide diversification benefits when added to a<br />portfolio consisting of stock and bond funds (referred to as Specialty Funds).<br />The second stage involves the actual selection of underlying funds to represent<br />the asset classes based on underlying fund classifications, historical risk,<br />performance, and other factors. Within the stock fund allocations, MFS seeks to<br />diversify globally (by including domestic and international underlying funds),<br />in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds) and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of November 1, 2012, the fund's target allocation among asset classes and the<br />underlying funds was:<br /><br />Bond Funds:                             5%<br />MFS Inflation-Adjusted Bond Fund        3%<br />MFS Research Bond Fund                  3%<br />Specialty Funds:                       10%<br />MFS Commodity Strategy Fund             5%<br />MFS Global Real Estate Fund             5%<br />International Stock Funds:             28%<br />MFS Emerging Markets Equity Fund        2%<br />MFS International Growth Fund           7%<br />MFS International New Discovery Fund    4%<br />MFS International Value Fund            7%<br />MFS Research International Fund         8%<br />U.S. Stock Funds:                      57%<br />MFS Growth Fund                        12%<br />MFS Mid Cap Growth Fund                10%<br />MFS Mid Cap Value Fund                 10%<br />MFS New Discovery Fund                  3%<br />MFS New Discovery Value Fund            3%<br />MFS Research Fund                       8%<br />MFS Value Fund                         12%<br /><br />*  The target asset class and underlying fund allocations presented in the table<br />are rounded.<br /><br />The asset class allocations, as well as the underlying funds and their target<br />weightings, are based on an allocation strategy designed for investors with the<br />approximate retirement year in the fund's name. Investors should also consider<br />their age, personal circumstances, risk tolerance, and overall investment<br />strategy and allocation. The asset allocation strategy will become increasingly<br />conservative over time.<br /><br />Upon reaching its stated target year, the fund's allocation strategy will be<br />aligned with the allocation strategy of the MFS Lifetime Retirement Income<br />Fund.  It is expected that the fund will be combined with the MFS Lifetime<br />Retirement Income Fund within five years of the date that its asset allocation<br />strategy matches the asset allocation strategy of the MFS Lifetime Retirement<br />Income Fund.  The chart below illustrates how the asset allocation strategy of<br />the fund will change over time.<br /><br />                                  ASSET CLASS WEIGHTS FOR TARGET DATE FUNDS<br /><br />71% Bond Funds<br />4%  Specialty Funds<br />5%  International Stock Funds<br />20% U.S. Stock Funds<br /><br /><br />U.S. Stock Funds                          Years Before Target Date                                Target Date      Years After Target Date  <br />                      55     50     45     40     35    30     25     20     15     10     5             0                  5     10<br />Asset class weight%   57%    57%    57%    57%    57%   57%    57%    54.5%  52%    41%   28%           20%                 20%   20%<br /><br /><br />International Stock Funds                 Years Before Target Date                                Target Date       Years After Target Date<br /><br />                     55     50     45     40     35     30     25     20     15     10     5             0                  5     10      <br />Asset class weight%  28%    28%    28%    28%    28%    28%    28%    24%    20%    13%    8%            5%                 5%    5%<br /><br /><br />Specialty Funds                           Years Before Target Date                                 Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10         <br />Asset class weight%  10%    10%    10%    10%    10%    10%    10%    9%     8%     6%     4%           4%                   4%    4%  <br /><br /><br />Bond Funds                               Years Before Target Date                                  Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10     <br />Asset class weight%  5%     5%     5%     5%     5%     5%     5%     12.5%  20%    40%    60%          71%                 71%    71%</tt>
Summary of Key Information
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.
Example
The annual fund operating expenses are based on estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current fiscal year expressed as a percentage of the fund's estimated average net assets during the period.
The bar chart and performance table are not included because the fund has not had a full calendar year of operations.
Investment Objective
As with any mutual fund, the fund may not achieve its objective and/or you could
lose money on your investment in the fund, including near or after the target date.
Principal Risks
Shareholder Fees (fees paid directly from your investment):
2013-10-31
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Performance Information
50000
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover
<tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund, including near or after the target<br />date.  There is no guarantee that the fund will provide income at or through <br />retirement. An investment in the fund is not a bank deposit and is not insured <br />or guaranteed by the Federal Deposit Insurance Corporation or any other <br />governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk:  MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk:  MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategy and may not achieve its objective.<br /><br />Stock Market/Company Risk:  Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor perceptions <br />of these conditions. The price of an equity security can decrease significantly in <br />response to these conditions, and these conditions can affect a single issuer or <br />type of security, issuers within a broad market sector, industry or geographic <br />region, or the market in general.<br /><br />Foreign and Emerging Markets Risk:  Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, and less developed legal, regulatory, and accounting<br />systems, and greater political, social, and economic instability than developed<br />markets.<br /><br />Currency Risk:  The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Interest Rate Risk:  The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk:  The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Prepayment/Extension Risk:  Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk:  Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. If <br />inflation is negative, principal and income can both decline.<br /><br />Municipal Risk:  The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Commodity Risk:  The value of commodities may be more volatile than the value of<br />equity securities or debt instruments and their value may be affected by changes<br />in overall market movements, commodity index volatility, changes in interest<br />rates, or factors affecting a particular industry or commodity. The price of a<br />commodity may be affected by demand/supply imbalances in the market for the<br />commodity.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real<br />estate-related securities include certain risks associated with the direct<br />ownership of real estate and the real estate industry in general. These include<br />risks related to general, regional and local economic conditions; fluctuations<br />in interest rates; property tax rates, zoning laws, environmental regulations<br />and other governmental action; cash flow dependency; increased operating<br />expenses; lack of availability of mortgage funds; losses due to natural<br />disasters; overbuilding; losses due to casualty or condemnation; changes in<br />property values and rental rates; and other factors.  The securities of smaller<br />real estate-related issuers can be more volatile and less liquid than securities<br />of larger issuers and their issuers can have more limited financial resources.<br /><br />Derivatives Risk:  Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.  Derivatives can involve leverage.<br /><br />Leveraging Risk:  Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk:  Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk:  It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt>
Fees and Expenses
Principal Investment Strategies
<tt>The bar chart and performance table are not included because the fund has not<br />had a full calendar year of operations.</tt>
<tt>This table describes the fees and expenses that you may pay when you buy and<br />hold shares of the fund. The annual fund operating expenses are based on<br />estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current<br />fiscal year expressed as a percentage of the fund's estimated average net assets<br />during the period.<br /><br />You may qualify for sales charge reductions if you and certain members of your<br />family invest, or agree to invest in the future, at least $50,000 in MFS Funds.<br />More information about these and other waivers and reductions is available from<br />your financial intermediary and in "Sales Charges and Waivers or Reductions" on<br />page 11 of the fund's prospectus and "Waivers of Sales Charges" on page I-13 of<br />the fund's statement of additional information Part I.</tt>
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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.
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<div style="display:none">~ http://www.mfs.com/role/ShareholderFeesData_S000038776Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
LFIUX
0.0000
87
1007
-0.0354
<tt>R4</tt>
0.0354
0.0000
0.0000
0.0085
0.0439
<tt>Class R4 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LFITX
0.0000
112
1080
-0.0354
<tt>R3</tt>
0.0354
0.0000
0.0025
0.0110
0.0464
<tt>Class R3 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LFISX
0.0000
137
1152
-0.0354
<tt>R2</tt>
0.0354
0.0000
0.0050
0.0135
0.0489
<tt>Class R2 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LFIRX
0.0000
188
1296
-0.0354
<tt>R1</tt>
0.0354
0.0000
0.0100
0.0185
0.0539
<tt>Class R1 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LFIIX
0.0000
87
1007
-0.0354
<tt>I</tt>
0.0354
0.0000
0.0000
0.0085
0.0439
<tt>Class I Shares</tt>
0.0085
<tt>I</tt>
0.0000
LFICX
0.0000
288
188
1296
-0.0354
<tt>C</tt>
0.0354
0.0000
1296
<tt>Class C Shares assuming no redemption at end of period</tt>
0.0100
0.0185
0.0539
<tt>Class C Shares assuming redemption at end of period</tt>
0.0085
<tt>C</tt>
0.0100
LFIBX
0.0000
588
188
1596
-0.0354
<tt>B</tt>
0.0354
0.0000
1296
<tt>Class B Shares assuming no redemption at end of period</tt>
0.0100
0.0185
0.0539
<tt>Class B Shares assuming redemption at end of period</tt>
0.0085
<tt>B</tt>
0.0400
LFIAX
0.0575
681
1593
-0.0354
<tt>A</tt>
0.0354
0.0000
0.0025
0.0110
0.0464
<tt>Class A Shares</tt>
0.0085
<tt>A</tt>
0.0100
<tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs and may result in higher taxes when <br />shares are held in a taxable account. These transaction costs, which are not <br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the <br />fund's performance.</tt>
<div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000038775Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<tt>The fund's investment objective is to seek a high level of total return<br />consistent with its asset allocation until the approximate retirement <br />year in the fund's name; thereafter, the fund will seek total return <br />through a combination of current income and capital appreciation. The <br />asset allocation of the fund will change over time.</tt>
<tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods (unless<br />otherwise indicated); your investment has a 5% return each year; and the fund's<br />operating expenses remain the same.</tt>
<tt>The fund is designed to provide diversification among different asset classes<br />for investors with the approximate retirement date in the fund's name. The fund<br />invests substantially all of its assets in other MFS mutual funds, referred to<br />as underlying funds. The underlying funds are selected following a two-stage<br />asset allocation process. The first stage is a strategic asset allocation to<br />establish the percentage of the fund's assets to be invested in the general<br />asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as<br />well as an allocation to underlying funds that have less traditional investment<br />strategies that MFS (Massachusetts Financial Services Company, the fund's<br />investment adviser) believes provide diversification benefits when added to a<br />portfolio consisting of stock and bond funds (referred to as Specialty Funds).<br />The second stage involves the actual selection of underlying funds to represent<br />the asset classes based on underlying fund classifications, historical risk,<br />performance, and other factors. Within the stock fund allocations, MFS seeks to<br />diversify globally (by including domestic and international underlying funds),<br />in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds) and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of November 1, 2012, the fund's target allocation among asset classes and the<br />underlying funds was:<br /><br />Bond Funds:                             5%<br />MFS Inflation-Adjusted Bond Fund        3%<br />MFS Research Bond Fund                  3%<br />Specialty Funds:                       10%<br />MFS Commodity Strategy Fund             5%<br />MFS Global Real Estate Fund             5%<br />International Stock Funds:             28%<br />MFS Emerging Markets Equity Fund        2%<br />MFS International Growth Fund           7%<br />MFS International New Discovery Fund    4%<br />MFS International Value Fund            7%<br />MFS Research International Fund         8%<br />U.S. Stock Funds:                      57%<br />MFS Growth Fund                        12%<br />MFS Mid Cap Growth Fund                10%<br />MFS Mid Cap Value Fund                 10%<br />MFS New Discovery Fund                  3%<br />MFS New Discovery Value Fund            3%<br />MFS Research Fund                       8%<br />MFS Value Fund                         12%<br /> <br />*  The target asset class and underlying fund allocations presented in the table<br />are rounded.<br /><br />The asset class allocations, as well as the underlying funds and their target<br />weightings, are based on an allocation strategy designed for investors with the<br />approximate retirement year in the fund's name. Investors should also consider<br />their age, personal circumstances, risk tolerance, and overall investment<br />strategy and allocation. The asset allocation strategy will become increasingly<br />conservative over time.<br /><br />Upon reaching its stated target year, the fund's allocation strategy will be<br />aligned with the allocation strategy of the MFS Lifetime Retirement Income<br />Fund.  It is expected that the fund will be combined with the MFS Lifetime<br />Retirement Income Fund within five years of the date that its asset allocation<br />strategy matches the asset allocation strategy of the MFS Lifetime Retirement<br />Income Fund.  The chart below illustrates how the asset allocation strategy of<br />the fund will change over time.<br /><br />                                  ASSET CLASS WEIGHTS FOR TARGET DATE FUNDS<br /><br />71% Bond Funds<br />4%  Specialty Funds<br />5%  International Stock Funds<br />20% U.S. Stock Funds<br /><br /><br />U.S. Stock Funds                          Years Before Target Date                                Target Date      Years After Target Date  <br />                      55     50     45     40     35    30     25     20     15     10     5             0                  5     10<br />Asset class weight%   57%    57%    57%    57%    57%   57%    57%    54.5%  52%    41%   28%           20%                 20%   20%<br /><br /><br />International Stock Funds                 Years Before Target Date                                Target Date       Years After Target Date<br /><br />                     55     50     45     40     35     30     25     20     15     10     5             0                  5     10      <br />Asset class weight%  28%    28%    28%    28%    28%    28%    28%    24%    20%    13%    8%            5%                 5%    5%<br /><br /><br />Specialty Funds                           Years Before Target Date                                 Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10         <br />Asset class weight%  10%    10%    10%    10%    10%    10%    10%    9%     8%     6%     4%           4%                   4%    4%  <br /><br /><br />Bond Funds                               Years Before Target Date                                  Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10     <br />Asset class weight%  5%     5%     5%     5%     5%     5%     5%     12.5%  20%    40%    60%          71%                 71%    71%</tt>
Summary of Key Information
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.
Example
The annual fund operating expenses are based on estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current fiscal year expressed as a percentage of the fund's estimated average net assets during the period.
The bar chart and performance table are not included because the fund has not had a full calendar year of operations.
Investment Objective
As with any mutual fund, the fund may not achieve its objective and/or you could
lose money on your investment in the fund, including near or after the target date.
Principal Risks
Shareholder Fees (fees paid directly from your investment):
2013-10-31
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Performance Information
50000
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover
<tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund, including near or after the target<br />date.  There is no guarantee that the fund will provide income at or through <br />retirement. An investment in the fund is not a bank deposit and is not insured or <br />guaranteed by the Federal Deposit Insurance Corporation or any other governmental <br />agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk:  MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk:  MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategy and may not achieve its objective.<br /><br />Stock Market/Company Risk:  Stock markets are volatile and can decline significantly <br />in response to issuer, market, economic, industry, political, regulatory, <br />geopolitical, and other conditions, as well as to investor perceptions of these <br />conditions. The price of an equity security can decrease significantly in response <br />to these conditions, and these conditions can affect a single issuer or type of <br />security, issuers within a broad market sector, industry or geographic region, <br />or the market in general.<br /><br />Foreign and Emerging Markets Risk:  Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, and less developed legal, regulatory, and accounting<br />systems, and greater political, social, and economic instability than developed<br />markets.<br /><br />Currency Risk:  The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Interest Rate Risk:  The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk:  The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Prepayment/Extension Risk:  Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk:  Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. If <br />inflation is negative, principal and income can both decline.<br /><br />Municipal Risk:  The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Commodity Risk:  The value of commodities may be more volatile than the value of<br />equity securities or debt instruments and their value may be affected by changes<br />in overall market movements, commodity index volatility, changes in interest<br />rates, or factors affecting a particular industry or commodity. The price of a<br />commodity may be affected by demand/supply imbalances in the market for the<br />commodity.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real estate-related <br />securities include certain risks associated with the direct ownership of real <br />estate and the real estate industry in general. These include risks related to <br />general, regional and local economic conditions; fluctuations in interest rates; <br />property tax rates, zoning laws, environmental regulations and other governmental <br />action; cash flow dependency; increased operating expenses; lack of availability <br />of mortgage funds; losses due to natural disasters; overbuilding; losses due to <br />casualty or condemnation; changes in property values and rental rates; and other <br />factors.  The securities of smaller real estate-related issuers can be more volatile <br />and less liquid than securities of larger issuers and their issuers can have more <br />limited financial resources.<br /><br />Derivatives Risk:  Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.  Derivatives can involve leverage.<br /><br />Leveraging Risk:  Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk:  Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk:  It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt>
Fees and Expenses
Principal Investment Strategies
<tt>The bar chart and performance table are not included because the fund has not<br />had a full calendar year of operations.</tt>
<tt>This table describes the fees and expenses that you may pay when you buy and<br />hold shares of the fund. The annual fund operating expenses are based on<br />estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current<br />fiscal year expressed as a percentage of the fund's estimated average net assets<br />during the period.<br /><br />You may qualify for sales charge reductions if you and certain members of your<br />family invest, or agree to invest in the future, at least $50,000 in MFS Funds.<br />More information about these and other waivers and reductions is available from<br />your financial intermediary and in "Sales Charges and Waivers or Reductions" on<br />page 11 of the fund's prospectus and "Waivers of Sales Charges" on page I-13 of<br />the fund's statement of additional information Part I.</tt>
<div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000038775Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
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.
<div style="display:none">~ http://www.mfs.com/role/ExpenseExampleNoRedemption_S000038775Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<div style="display:none">~ http://www.mfs.com/role/ShareholderFeesData_S000038775Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
LTMUX
0.0000
87
786
-0.0245
<tt>R4</tt>
0.0245
0.0000
0.0000
0.0085
0.0330
<tt>Class R4 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LTMTX
0.0000
112
861
-0.0245
<tt>R3</tt>
0.0245
0.0000
0.0025
0.0110
0.0355
<tt>Class R3 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LTMSX
0.0000
137
935
-0.0245
<tt>R2</tt>
0.0245
0.0000
0.0050
0.0135
0.0380
<tt>Class R2 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LTMRX
0.0000
188
1081
-0.0245
<tt>R1</tt>
0.0245
0.0000
0.0100
0.0185
0.0430
<tt>Class R1 Shares</tt>
0.0085
<tt>ALL R</tt>
0.0000
LTMKX
0.0000
87
786
-0.0245
<tt>I</tt>
0.0245
0.0000
0.0000
0.0085
0.0330
<tt>Class I Shares</tt>
0.0085
<tt>I</tt>
0.0000
LTMDX
0.0000
288
188
1081
-0.0245
<tt>C</tt>
0.0245
0.0000
1081
<tt>Class C Shares assuming no redemption at end of period</tt>
0.0100
0.0185
0.0430
<tt>Class C Shares assuming redemption at end of period</tt>
0.0085
<tt>C</tt>
0.0100
LTMBX
0.0000
588
188
1381
-0.0245
<tt>B</tt>
0.0245
0.0000
1081
<tt>Class B Shares assuming no redemption at end of period</tt>
0.0100
0.0185
0.0430
<tt>Class B Shares assuming redemption at end of period</tt>
0.0085
<tt>B</tt>
0.0400
LTMAX
0.0575
681
1386
-0.0245
<tt>A</tt>
0.0245
0.0000
0.0025
0.0110
0.0355
<tt>Class A Shares</tt>
0.0085
<tt>A</tt>
0.0100
<tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs and may result in higher taxes when <br />shares are held in a taxable account. These transaction costs, which are not <br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the <br />fund's performance.</tt>
<div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000038774Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<tt>The fund's investment objective is to seek a high level of total return<br />consistent with its asset allocation until the approximate retirement <br />year in the fund's name; thereafter, the fund will seek total return <br />through a combination of current income and capital appreciation. The <br />asset allocation of the fund will change over time.</tt>
<tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods (unless<br />otherwise indicated); your investment has a 5% return each year; and the fund's<br />operating expenses remain the same.</tt>
<tt>The fund is designed to provide diversification among different asset classes<br />for investors with the approximate retirement date in the fund's name. The fund<br />invests substantially all of its assets in other MFS mutual funds, referred to<br />as underlying funds. The underlying funds are selected following a two-stage<br />asset allocation process. The first stage is a strategic asset allocation to<br />establish the percentage of the fund's assets to be invested in the general<br />asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as<br />well as an allocation to underlying funds that have less traditional investment<br />strategies that MFS (Massachusetts Financial Services Company, the fund's<br />investment adviser) believes provide diversification benefits when added to a<br />portfolio consisting of stock and bond funds (referred to as Specialty Funds).<br />The second stage involves the actual selection of underlying funds to represent<br />the asset classes based on underlying fund classifications, historical risk,<br />performance, and other factors. Within the stock fund allocations, MFS seeks to<br />diversify globally (by including domestic and international underlying funds),<br />in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds) and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of November 1, 2012, the fund's target allocation among asset classes and the<br />underlying funds was:<br /><br />Bond Funds:                             8%  <br />MFS Emerging Markets Debt Fund          1%  <br />MFS Global Bond Fund                    1%  <br />MFS High Income Fund                    1%  <br />MFS Inflation-Adjusted Bond Fund        3%  <br />MFS Research Bond Fund                  3%  <br />Specialty Funds:                       10%  <br />MFS Absolute Return Fund                0%**<br />MFS Commodity Strategy Fund             5%  <br />MFS Global Real Estate Fund             5%  <br />International Stock Funds:             26%  <br />MFS Emerging Markets Equity Fund        2%  <br />MFS International Growth Fund           7%  <br />MFS International New Discovery Fund    4%  <br />MFS International Value Fund            7%  <br />MFS Research International Fund         8%  <br />U.S. Stock Funds:                      56%  <br />MFS Growth Fund                        12%  <br />MFS Mid Cap Growth Fund                10%  <br />MFS Mid Cap Value Fund                 10%  <br />MFS New Discovery Fund                  2%  <br />MFS New Discovery Value Fund            2%  <br />MFS Research Fund                       8%  <br />MFS Value Fund                         12%  <br /><br />*  The target asset class and underlying fund allocations presented in the table <br />are rounded.<br /> <br />** Less than 0.5%<br /><br />The asset class allocations, as well as the underlying funds and their target<br />weightings, are based on an allocation strategy designed for investors with the<br />approximate retirement year in the fund's name. Investors should also consider<br />their age, personal circumstances, risk tolerance, and overall investment<br />strategy and allocation. The asset allocation strategy will become increasingly<br />conservative over time.<br /><br />Upon reaching its stated target year, the fund's allocation strategy will be<br />aligned with the allocation strategy of the MFS Lifetime Retirement Income<br />Fund.  It is expected that the fund will be combined with the MFS Lifetime<br />Retirement Income Fund within five years of the date that its asset allocation<br />strategy matches the asset allocation strategy of the MFS Lifetime Retirement<br />Income Fund.  The chart below illustrates how the asset allocation strategy of<br />the fund will change over time.<br /><br />                                  ASSET CLASS WEIGHTS FOR TARGET DATE FUNDS<br /><br />71% Bond Funds<br />4%  Specialty Funds<br />5%  International Stock Funds<br />20% U.S. Stock Funds<br /><br /><br />U.S. Stock Funds                          Years Before Target Date                                Target Date      Years After Target Date  <br />                      55     50     45     40     35    30     25     20     15     10     5             0                  5     10<br />Asset class weight%   57%    57%    57%    57%    57%   57%    57%    54.5%  52%    41%   28%           20%                 20%   20%<br /><br /><br />International Stock Funds                 Years Before Target Date                                Target Date       Years After Target Date<br /><br />                     55     50     45     40     35     30     25     20     15     10     5             0                  5     10      <br />Asset class weight%  28%    28%    28%    28%    28%    28%    28%    24%    20%    13%    8%            5%                 5%    5%<br /><br /><br />Specialty Funds                           Years Before Target Date                                 Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10         <br />Asset class weight%  10%    10%    10%    10%    10%    10%    10%    9%     8%     6%     4%           4%                   4%    4%  <br /><br /><br />Bond Funds                               Years Before Target Date                                  Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10     <br />Asset class weight%  5%     5%     5%     5%     5%     5%     5%     12.5%  20%    40%    60%          71%                 71%    71%</tt>
Summary of Key Information
Example
The annual fund operating expenses are based on estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current fiscal year expressed as a percentage of the fund's estimated average net assets during the period.
The bar chart and performance table are not included because the fund has not had a full calendar year of operations.
Investment Objective
As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund, including near or after the target date.
Principal Risks
Shareholder Fees (fees paid directly from your investment):
2013-10-31
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Performance Information
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover
<tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund, including near or after the target<br />date.  There is no guarantee that the fund will provide income at or through<br />retirement. An investment in the fund is not a bank deposit and is not insured<br />or guaranteed by the Federal Deposit Insurance Corporation or any other<br />governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk:  MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk:  MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategy and may not achieve its objective.<br /><br />Stock Market/Company Risk:  Stock markets are volatile and can decline significantly <br />in response to issuer, market, economic, industry, political, regulatory, geopolitical, <br />and other conditions, as well as to investor perceptions of these conditions. The <br />price of an equity security can decrease significantly in response to these <br />conditions, and these conditions can affect a single issuer or type of security, <br />issuers within a broad market sector, industry or geographic region, or the market <br />in general.<br /><br />Foreign and Emerging Markets Risk:  Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, and less developed legal, regulatory, and accounting<br />systems, and greater political, social, and economic instability than developed<br />markets.<br /><br />Currency Risk:  The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Interest Rate Risk:  The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk:  The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt instruments.<br /><br />Prepayment/Extension Risk:  Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk:  Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. If <br />inflation is negative, principal and income can both decline.<br /><br />Municipal Risk:  The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Commodity Risk:  The value of commodities may be more volatile than the value of<br />equity securities or debt instruments and their value may be affected by changes<br />in overall market movements, commodity index volatility, changes in interest<br />rates, or factors affecting a particular industry or commodity. The price of a<br />commodity may be affected by demand/supply imbalances in the market for the<br />commodity.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real estate-related <br />securities include certain risks associated with the direct ownership of real <br />estate and the real estate industry in general. These include risks related to <br />general, regional and local economic conditions; fluctuations in interest rates; <br />property tax rates, zoning laws, environmental regulations and other governmental <br />action; cash flow dependency; increased operating expenses; lack of availability <br />of mortgage funds; losses due to natural disasters; overbuilding; losses due to <br />casualty or condemnation; changes in property values and rental rates; and other <br />factors. The securities of smaller real estate-related issuers can be more volatile <br />and less liquid than securities of larger issuers and their issuers can have more <br />limited financial resources.<br /><br />Derivatives Risk:  Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.  Derivatives can involve leverage.<br /><br />Leveraging Risk:  Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk:  Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk:  It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt>
Fees and Expenses
Principal Investment Strategies
<tt>The bar chart and performance table are not included because the fund has not<br />had a full calendar year of operations.</tt>
<tt>This table describes the fees and expenses that you may pay when you buy and<br />hold shares of the fund. The annual fund operating expenses are based on<br />estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current<br />fiscal year expressed as a percentage of the fund's estimated average net assets<br />during the period.<br /><br />You may qualify for sales charge reductions if you and certain members of your<br />family invest, or agree to invest in the future, at least $50,000 in MFS Funds.<br />More information about these and other waivers and reductions is available from<br />your financial intermediary and in "Sales Charges and Waivers or Reductions" on<br />page 11 of the fund's prospectus and "Waivers of Sales Charges" on page I-13 of<br />the fund's statement of additional information Part I.</tt>
<div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000038774Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
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.
<div style="display:none">~ http://www.mfs.com/role/ExpenseExampleNoRedemption_S000038774Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<div style="display:none">~ http://www.mfs.com/role/ShareholderFeesData_S000038774Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
LFEUX
0.0000
86
590
-0.0152
<tt>R4</tt>
0.0152
0.0000
0.0000
0.0084
0.0236
<tt>Class R4 Shares</tt>
0.0084
<tt>ALL R</tt>
0.0000
LFETX
0.0000
111
667
-0.0152
<tt>R3</tt>
0.0152
0.0000
0.0025
0.0109
0.0261
<tt>Class R3 Shares</tt>
0.0084
<tt>ALL R</tt>
0.0000
LFESX
0.0000
136
742
-0.0152
<tt>R2</tt>
0.0152
0.0000
0.0050
0.0134
0.0286
<tt>Class R2 Shares</tt>
0.0084
<tt>ALL R</tt>
0.0000
LFERX
0.0000
187
892
-0.0152
<tt>R1</tt>
0.0152
0.0000
0.0100
0.0184
0.0336
<tt>Class R1 Shares</tt>
0.0084
<tt>ALL R</tt>
0.0000
LFEDX
0.0000
86
590
-0.0152
<tt>I</tt>
0.0152
0.0000
0.0000
0.0084
0.0236
<tt>Class I Shares</tt>
0.0084
<tt>I</tt>
0.0000
LFECX
0.0000
287
187
892
-0.0152
<tt>C</tt>
0.0152
0.0000
892
<tt>Class C Shares assuming no redemption at end of period</tt>
0.0100
0.0184
0.0336
<tt>Class C Shares assuming redemption at end of period</tt>
0.0084
<tt>C</tt>
0.0100
LFEBX
0.0000
587
187
1192
-0.0152
<tt>B</tt>
0.0152
0.0000
892
<tt>Class B Shares assuming no redemption at end of period</tt>
0.0100
0.0184
0.0336
<tt>Class B Shares assuming redemption at end of period</tt>
0.0084
<tt>B</tt>
0.0400
LFEAX
0.0575
680
1203
-0.0152
<tt>A</tt>
0.0152
0.0000
0.0025
0.0109
0.0261
<tt>Class A Shares</tt>
0.0084
<tt>A</tt>
0.0100
<tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate may<br />indicate higher transaction costs and may result in higher taxes when shares are<br />held in a taxable account. These transaction costs, which are not reflected in<br />"Annual Fund Operating Expenses" or in the "Example," affect the fund's<br />performance.</tt>
<div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000038773Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<tt>The fund's investment objective is to seek a high level of total return<br />consistent with its asset allocation until the approximate retirement <br />year in the fund's name; thereafter, the fund will seek total return <br />through a combination of current income and capital appreciation. The <br />asset allocation of the fund will change over time.</tt>
<tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods (unless<br />otherwise indicated); your investment has a 5% return each year; and the fund's<br />operating expenses remain the same.</tt>
<tt>The fund is designed to provide diversification among different asset classes<br />for investors with the approximate retirement date in the fund's name. The fund<br />invests substantially all of its assets in other MFS mutual funds, referred to<br />as underlying funds. The underlying funds are selected following a two-stage<br />asset allocation process. The first stage is a strategic asset allocation to<br />establish the percentage of the fund's assets to be invested in the general<br />asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as<br />well as an allocation to underlying funds that have less traditional investment<br />strategies that MFS (Massachusetts Financial Services Company, the fund's<br />investment adviser) believes provide diversification benefits when added to a<br />portfolio consisting of stock and bond funds (referred to as Specialty Funds).<br />The second stage involves the actual selection of underlying funds to represent<br />the asset classes based on underlying fund classifications, historical risk,<br />performance, and other factors. Within the stock fund allocations, MFS seeks to<br />diversify globally (by including domestic and international underlying funds),<br />in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds) and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of November 1, 2012, the fund's target allocation among asset classes and the<br />underlying funds was:<br /><br />Bond Funds:                            28%<br />MFS Emerging Markets Debt Fund          3%<br />MFS Global Bond Fund                    4%<br />MFS Government Securities Fund          4%<br />MFS High Income Fund                    5%<br />MFS Inflation-Adjusted Bond Fund        5%<br />MFS Research Bond Fund                  7%<br />Specialty Funds:                        7%<br />MFS Absolute Return Fund                1%<br />MFS Commodity Strategy Fund             4%<br />MFS Global Real Estate Fund             3%<br />International Stock Funds:             17%<br />MFS Emerging Markets Equity Fund        1%<br />MFS International Growth Fund           4%<br />MFS International New Discovery Fund    2%<br />MFS International Value Fund            4%<br />MFS Research International Fund         7%<br />U.S. Stock Funds:                      47%<br />MFS Growth Fund                        10%<br />MFS Mid Cap Growth Fund                 8%<br />MFS Mid Cap Value Fund                  8%<br />MFS New Discovery Fund                  2%<br />MFS New Discovery Value Fund            2%<br />MFS Research Fund                       8%<br />MFS Value Fund                         10%<br /><br />*  The target asset class and underlying fund allocations presented in the table<br />are rounded.<br /><br />The asset class allocations, as well as the underlying funds and their target<br />weightings, are based on an allocation strategy designed for investors with the<br />approximate retirement year in the fund's name. Investors should also consider<br />their age, personal circumstances, risk tolerance, and overall investment<br />strategy and allocation. The asset allocation strategy will become increasingly<br />conservative over time.<br /><br />Upon reaching its stated target year, the fund's allocation strategy will be<br />aligned with the allocation strategy of the MFS Lifetime Retirement Income<br />Fund.  It is expected that the fund will be combined with the MFS Lifetime<br />Retirement Income Fund within five years of the date that its asset allocation<br />strategy matches the asset allocation strategy of the MFS Lifetime Retirement<br />Income Fund.  The chart below illustrates how the asset allocation strategy of<br />the fund will change over time.<br /><br />                                  ASSET CLASS WEIGHTS FOR TARGET DATE FUNDS<br /><br />71% Bond Funds<br />4%  Specialty Funds<br />5%  International Stock Funds<br />20% U.S. Stock Funds<br /><br /><br />U.S. Stock Funds                          Years Before Target Date                                Target Date      Years After Target Date  <br />                      55     50     45     40     35    30     25     20     15     10     5             0                  5     10<br />Asset class weight%   57%    57%    57%    57%    57%   57%    57%    54.5%  52%    41%   28%           20%                 20%   20%<br /><br /><br />International Stock Funds                 Years Before Target Date                                Target Date       Years After Target Date<br /><br />                     55     50     45     40     35     30     25     20     15     10     5             0                  5     10      <br />Asset class weight%  28%    28%    28%    28%    28%    28%    28%    24%    20%    13%    8%            5%                 5%    5%<br /><br /><br />Specialty Funds                           Years Before Target Date                                 Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10         <br />Asset class weight%  10%    10%    10%    10%    10%    10%    10%    9%     8%     6%     4%           4%                   4%    4%  <br /><br /><br />Bond Funds                               Years Before Target Date                                  Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10     <br />Asset class weight%  5%     5%     5%     5%     5%     5%     5%     12.5%  20%    40%    60%          71%                 71%    71%</tt>
Summary of Key Information
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.
Example
The annual fund operating expenses are based on estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current fiscal year expressed as a percentage of the fund's estimated average net assets during the period.
The bar chart and performance table are not included because the fund has not had a full calendar year of operations.
Investment Objective
As with any mutual fund, the fund may not achieve its objective and/or you could
lose money on your investment in the fund, including near or after the target date.
Principal Risks
Shareholder Fees (fees paid directly from your investment):
2013-10-31
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Performance Information
50000
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover
<tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund, including near or after the target date.  <br />There is no guarantee that the fund will provide income at or through retirement. <br />An investment in the fund is not a bank deposit and is not insured or guaranteed <br />by the Federal Deposit Insurance Corporation or any other governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk:  MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk:  MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategy and may not achieve its objective.<br /><br />Stock Market/Company Risk:  Stock markets are volatile and can decline significantly <br />in response to issuer, market, economic, industry, political, regulatory, geopolitical, <br />and other conditions, as well as to investor perceptions of these conditions. The <br />price of an equity security can decrease significantly in response to these <br />conditions, and these conditions can affect a single issuer or type of security, <br />issuers within a broad market sector, industry or geographic region, or the market <br />in general.<br /><br />Foreign and Emerging Markets Risk:  Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, and less developed legal, regulatory, and accounting<br />systems, and greater political, social, and economic instability than developed<br />markets.<br /><br />Currency Risk:  The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Interest Rate Risk:  The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk:  The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Prepayment/Extension Risk:  Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk:  Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. If <br />inflation is negative, principal and income can both decline.<br /><br />Municipal Risk:  The price of a municipal instrument can be volatile and significantly <br />affected by adverse tax or court rulings, legislative or political changes, changes in <br />specific or general market and economic conditions, and the financial condition of <br />municipal issuers and insurers. Because many municipal instruments are issued to <br />finance similar projects, conditions in these industries can significantly affect the <br />fund and the overall municipal market.<br /><br />Commodity Risk:  The value of commodities may be more volatile than the value of<br />equity securities or debt instruments and their value may be affected by changes<br />in overall market movements, commodity index volatility, changes in interest<br />rates, or factors affecting a particular industry or commodity. The price of a<br />commodity may be affected by demand/supply imbalances in the market for the<br />commodity.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real estate-related <br />securities include certain risks associated with the direct ownership of real estate <br />and the real estate industry in general. These include risks related to general, <br />regional and local economic conditions; fluctuations in interest rates; property <br />tax rates, zoning laws, environmental regulations and other governmental action; <br />cash flow dependency; increased operating expenses; lack of availability of mortgage <br />funds; losses due to natural disasters; overbuilding; losses due to casualty or <br />condemnation; changes in property values and rental rates; and other factors.  The <br />securities of smaller real estate-related issuers can be more volatile and less <br />liquid than securities of larger issuers and their issuers can have more limited <br />financial resources.<br /><br />Derivatives Risk:  Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.  Derivatives can involve leverage.<br /><br />Leveraging Risk:  Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk:  Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk:  It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt>
Fees and Expenses
Principal Investment Strategies
<tt>The bar chart and performance table are not included because the fund has not<br />had a full calendar year of operations.</tt>
<tt>This table describes the fees and expenses that you may pay when you buy and<br />hold shares of the fund. The annual fund operating expenses are based on<br />estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current<br />fiscal year expressed as a percentage of the fund's estimated average net assets<br />during the period.<br /><br />You may qualify for sales charge reductions if you and certain members of your<br />family invest, or agree to invest in the future, at least $50,000 in MFS Funds.<br />More information about these and other waivers and reductions is available from<br />your financial intermediary and in "Sales Charges and Waivers or Reductions" on<br />page 11 of the fund's prospectus and "Waivers of Sales Charges" on page I-13 of<br />the fund's statement of additional information Part I.</tt>
<div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000038773Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
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.
<div style="display:none">~ http://www.mfs.com/role/ExpenseExampleNoRedemption_S000038773Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<div style="display:none">~ http://www.mfs.com/role/ShareholderFeesData_S000038773Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
LTTAX
0.0575
675
1187
-0.0151
<tt>A</tt>
0.0151
0.0000
0.0025
0.0104
0.0255
<tt>Class A Shares</tt>
0.0079
<tt>A</tt>
0.0100
LTTUX
0.0000
81
573
-0.0151
<tt>R4</tt>
0.0151
0.0000
0.0000
0.0079
0.0230
<tt>Class R4 Shares</tt>
0.0079
<tt>ALL R</tt>
0.0000
LTTTX
0.0000
106
649
-0.0151
<tt>R3</tt>
0.0151
0.0000
0.0025
0.0104
0.0255
<tt>Class R3 Shares</tt>
0.0079
<tt>ALL R</tt>
0.0000
LTTSX
0.0000
131
725
-0.0151
<tt>R2</tt>
0.0151
0.0000
0.0050
0.0129
0.0280
<tt>Class R2 Shares</tt>
0.0079
<tt>ALL R</tt>
0.0000
LTTRX
0.0000
182
875
-0.0151
<tt>R1</tt>
0.0151
0.0000
0.0100
0.0179
0.0330
<tt>Class R1 Shares</tt>
0.0079
<tt>ALL R</tt>
0.0000
LTTIX
0.0000
81
573
-0.0151
<tt>I</tt>
0.0151
0.0000
0.0000
0.0079
0.0230
<tt>Class I Shares</tt>
0.0079
<tt>I</tt>
0.0000
LTTCX
0.0000
282
182
875
-0.0151
<tt>C</tt>
0.0151
0.0000
875
<tt>Class C Shares assuming no redemption at end of period</tt>
0.0100
0.0179
0.0330
<tt>Class C Shares assuming redemption at end of period</tt>
0.0079
<tt>C</tt>
0.0100
LTTBX
0.0000
582
182
1175
-0.0151
<tt>B</tt>
0.0151
0.0000
875
<tt>Class B Shares assuming no redemption at end of period</tt>
0.0100
0.0179
0.0330
<tt>Class B Shares assuming redemption at end of period</tt>
0.0079
<tt>B</tt>
0.0400
<tt>The fund pays transaction costs, such as commissions, when it buys and sells<br />securities (or "turns over" its portfolio). A higher portfolio turnover rate <br />may indicate higher transaction costs and may result in higher taxes when <br />shares are held in a taxable account. These transaction costs, which are not <br />reflected in "Annual Fund Operating Expenses" or in the "Example," affect the <br />fund's performance.</tt>
<div style="display:none">~ http://www.mfs.com/role/ExpenseExample_S000038772Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<tt>The fund's investment objective is to seek a high level of total return<br />consistent with its asset allocation until the approximate retirement <br />year in the fund's name; thereafter, the fund will seek total return <br />through a combination of current income and capital appreciation. The <br />asset allocation of the fund will change over time.</tt>
<tt>This example is intended to help you compare the cost of investing in the fund<br />with the cost of investing in other mutual funds.<br /><br />The example assumes that: you invest $10,000 in the fund for the time periods<br />indicated and you redeem your shares at the end of the time periods (unless<br />otherwise indicated); your investment has a 5% return each year; and the fund's<br />operating expenses remain the same.</tt>
<tt>The fund is designed to provide diversification among different asset classes<br />for investors with the approximate retirement date in the fund's name. The fund<br />invests substantially all of its assets in other MFS mutual funds, referred to<br />as underlying funds. The underlying funds are selected following a two-stage<br />asset allocation process. The first stage is a strategic asset allocation to<br />establish the percentage of the fund's assets to be invested in the general<br />asset classes of Bond Funds, International Stock Funds, and U.S. Stock Funds, as<br />well as an allocation to underlying funds that have less traditional investment<br />strategies that MFS (Massachusetts Financial Services Company, the fund's<br />investment adviser) believes provide diversification benefits when added to a<br />portfolio consisting of stock and bond funds (referred to as Specialty Funds).<br />The second stage involves the actual selection of underlying funds to represent<br />the asset classes based on underlying fund classifications, historical risk,<br />performance, and other factors. Within the stock fund allocations, MFS seeks to<br />diversify globally (by including domestic and international underlying funds),<br />in terms of market capitalization (by including large, mid, and small<br />capitalization underlying funds) and by style (by including both growth and<br />value underlying funds). Within the bond fund allocation, MFS includes<br />underlying funds with varying degrees of interest rate and credit exposure.<br /><br />As of November 1, 2012, the fund's target allocation among asset classes and the<br />underlying funds was:<br /><br />Bond Funds:                        65%<br />MFS Emerging Markets Debt Fund      2%<br />MFS Global Bond Fund                5%<br />MFS Government Securities Fund     10%<br />MFS High Income Fund                4%<br />MFS Inflation-Adjusted Bond Fund   10%<br />MFS Limited Maturity Fund          14%<br />MFS Research Bond Fund             19%<br />Specialty Funds:                    4%<br />MFS Absolute Return Fund            2%<br />MFS Commodity Strategy Fund         1%<br />MFS Global Real Estate Fund         1%<br />International Stock Funds:          7%<br />MFS International Growth Fund       2%<br />MFS International Value Fund        2%<br />MFS Research International Fund     4%<br />U.S. Stock Funds:                  25%<br />MFS Growth Fund                     5%<br />MFS Mid Cap Growth Fund             4%<br />MFS Mid Cap Value Fund              4%<br />MFS New Discovery Fund              1%<br />MFS New Discovery Value Fund        1%<br />MFS Research Fund                   5%<br />MFS Value Fund                      5%<br /> <br />* The target asset class and underlying fund allocations presented in the table<br />are rounded.<br /><br />The asset class allocations, as well as the underlying funds and their target<br />weightings, are based on an allocation strategy designed for investors with the<br />approximate retirement year in the fund's name. Investors should also consider<br />their age, personal circumstances, risk tolerance, and overall investment<br />strategy and allocation. The asset allocation strategy will become increasingly<br />conservative over time.<br /><br />Upon reaching its stated target year, the fund's allocation strategy will be<br />aligned with the allocation strategy of the MFS Lifetime Retirement Income<br />Fund.  It is expected that the fund will be combined with the MFS Lifetime<br />Retirement Income Fund within five years of the date that its asset allocation<br />strategy matches the asset allocation strategy of the MFS Lifetime Retirement<br />Income Fund.  The chart below illustrates how the asset allocation strategy of<br />the fund will change over time.<br /><br />                                  ASSET CLASS WEIGHTS FOR TARGET DATE FUNDS<br /><br />71% Bond Funds<br />4%  Specialty Funds<br />5%  International Stock Funds<br />20% U.S. Stock Funds<br /><br /><br />U.S. Stock Funds                          Years Before Target Date                                Target Date      Years After Target Date  <br />                      55     50     45     40     35    30     25     20     15     10     5             0                  5     10<br />Asset class weight%   57%    57%    57%    57%    57%   57%    57%    54.5%  52%    41%   28%           20%                 20%   20%<br /><br /><br />International Stock Funds                 Years Before Target Date                                Target Date       Years After Target Date<br /><br />                     55     50     45     40     35     30     25     20     15     10     5             0                  5     10      <br />Asset class weight%  28%    28%    28%    28%    28%    28%    28%    24%    20%    13%    8%            5%                 5%    5%<br /><br /><br />Specialty Funds                           Years Before Target Date                                 Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10         <br />Asset class weight%  10%    10%    10%    10%    10%    10%    10%    9%     8%     6%     4%           4%                   4%    4%  <br /><br /><br />Bond Funds                               Years Before Target Date                                  Target Date       Years After Target Date<br />                     55     50     45     40     35     30     25     20     15     10     5            0                    5     10     <br />Asset class weight%  5%     5%     5%     5%     5%     5%     5%     12.5%  20%    40%    60%          71%                 71%    71%</tt>
Summary of Key Information
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.
Example
The annual fund operating expenses are based on estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current fiscal year expressed as a percentage of the fund's estimated average net assets during the period.
The bar chart and performance table are not included because the fund has not had a full calendar year of operations.
Investment Objective
As with any mutual fund, the fund may not achieve its objective and/or you could
lose money on your investment in the fund, including near or after the target date.
Principal Risks
Shareholder Fees (fees paid directly from your investment):
2013-10-31
Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Performance Information
50000
Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover
<tt>As with any mutual fund, the fund may not achieve its objective and/or you could<br />lose money on your investment in the fund, including near or after the target<br />date.  There is no guarantee that the fund will provide income at or through<br />retirement. An investment in the fund is not a bank deposit and is not insured<br />or guaranteed by the Federal Deposit Insurance Corporation or any other<br />governmental agency.<br /><br />The principal risks of investing in the fund are:<br /><br />Investment Selection and Allocation Risk:  MFS' investment analysis, its<br />selection of investments, and its assessment of the risk/return potential of<br />asset classes and underlying funds may not produce the intended results and/or<br />can lead to an investment focus that results in the fund underperforming other<br />funds with similar investment strategies and/or underperforming the markets in<br />which the fund invests.<br /><br />Underlying Funds Risk:  MFS' strategy of investing in underlying funds exposes<br />the fund to the risks of the underlying funds. Each underlying fund pursues its<br />own investment objective and strategy and may not achieve its objective.<br /><br />Interest Rate Risk:  The price of a debt instrument falls when interest rates<br />rise and rises when interest rates fall. Instruments with longer maturities, or<br />that do not pay current interest, are more sensitive to interest rate changes.<br /><br />Credit Risk:  The price of a debt instrument depends, in part, on the credit<br />quality of the issuer, borrower, counterparty, or underlying collateral or<br />assets and the terms of the instrument. The price of a debt instrument can<br />decline in response to changes in the financial condition of the issuer,<br />borrower, counterparty, or underlying collateral or assets, or changes in<br />specific or general market, economic, industry, political, regulatory,<br />geopolitical, or other conditions.<br /><br />Lower quality debt instruments (commonly referred to as "high yield securities"<br />or "junk bonds") can involve a substantially greater risk of default or can<br />already be in default, and their values can decline significantly. Lower quality<br />debt instruments are regarded as having predominantly speculative characteristics. <br />Lower quality debt instruments tend to be more sensitive to adverse news about <br />the issuer, or the market or economy in general, than higher quality debt <br />instruments.<br /><br />Foreign and Emerging Markets Risk:  Exposure to foreign markets, especially<br />emerging markets, through issuers or currencies can involve additional risks<br />relating to market, economic, political, regulatory, geopolitical, or other<br />conditions. These factors can make foreign investments, especially those in<br />emerging markets, more volatile and less liquid than U.S. investments. In<br />addition, foreign markets can react differently to these conditions than the<br />U.S. market. Emerging markets can have less developed markets, greater custody<br />and operational risk, and less developed legal, regulatory, and accounting<br />systems, and greater political, social, and economic instability than developed<br />markets.<br /><br />Currency Risk:  The value of foreign currencies relative to the U.S. dollar<br />fluctuates in response to market, economic, political, regulatory, geopolitical<br />or other conditions, and a decline in the value of a foreign currency versus the<br />U.S. dollar reduces the value in U.S. dollars of investments denominated in that<br />foreign currency.<br /><br />Prepayment/Extension Risk:  Instruments subject to prepayment and/or extension<br />can reduce the potential for gain for the instrument's holders if the instrument<br />is prepaid and increase the potential for loss if the maturity of the instrument<br />is extended.<br /><br />Inflation-Adjusted Debt Instruments Risk:  Interest payments on inflation-adjusted <br />debt instruments can be unpredictable and vary based on the level of inflation. <br />If inflation is negative, principal and income can both decline.<br /><br />Municipal Risk:  The price of a municipal instrument can be volatile and<br />significantly affected by adverse tax or court rulings, legislative or political<br />changes, changes in specific or general market and economic conditions, and the<br />financial condition of municipal issuers and insurers. Because many municipal<br />instruments are issued to finance similar projects, conditions in these<br />industries can significantly affect the fund and the overall municipal market.<br /><br />Commodity Risk:  The value of commodities may be more volatile than the value of<br />equity securities or debt instruments and their value may be affected by changes<br />in overall market movements, commodity index volatility, changes in interest<br />rates, or factors affecting a particular industry or commodity. The price of a<br />commodity may be affected by demand/supply imbalances in the market for the<br />commodity.<br /><br />Real Estate-Related Investment Risk: The risks of investing in real estate-related <br />securities include certain risks associated with the direct ownership of real <br />estate and the real estate industry in general. These include risks related to <br />general, regional and local economic conditions; fluctuations in interest rates; <br />property tax rates, zoning laws, environmental regulations and other governmental <br />action; cash flow dependency; increased operating expenses; lack of availability <br />of mortgage funds; losses due to natural disasters; overbuilding; losses due to <br />casualty or condemnation; changes in property values and rental rates; and other <br />factors.  The securities of smaller real estate-related issuers can be more <br />volatile and less liquid than securities of larger issuers and their issuers can <br />have more limited financial resources.<br /> <br />Stock Market/Company Risk:  Stock markets are volatile and can decline<br />significantly in response to issuer, market, economic, industry, political,<br />regulatory, geopolitical, and other conditions, as well as to investor<br />perceptions of these conditions. The price of an equity security can decrease<br />significantly in response to these conditions, and these conditions can affect a<br />single issuer or type of security, issuers within a broad market sector,<br />industry or geographic region, or the market in general.<br /><br />Derivatives Risk:  Derivatives can be highly volatile and involve risks in<br />addition to the risks of the underlying indicator(s) on which the derivative is<br />based. Gains or losses from derivatives can be substantially greater than the<br />derivatives' original cost.  Derivatives can involve leverage.<br /><br />Leveraging Risk:  Leverage involves investment exposure in an amount exceeding<br />the initial investment. Leverage can cause increased volatility by magnifying<br />gains or losses.<br /><br />Counterparty and Third Party Risk:  Transactions involving a counterparty or<br />third party other than the issuer of the instrument are subject to the credit<br />risk of the counterparty or third party, and to the counterparty's or third<br />party's ability to perform in accordance with the terms of the transaction.<br /><br />Liquidity Risk:  It may not be possible to sell certain investments, types of<br />investments, and/or segments of the market at any particular time or at an<br />acceptable price.</tt>
Fees and Expenses
Principal Investment Strategies
<tt>The bar chart and performance table are not included because the fund has not<br />had a full calendar year of operations.</tt>
<tt>This table describes the fees and expenses that you may pay when you buy and<br />hold shares of the fund. The annual fund operating expenses are based on<br />estimated "Other Expenses" and "Acquired Fund Fees and Expenses" for the current<br />fiscal year expressed as a percentage of the fund's estimated average net assets<br />during the period.<br /><br />You may qualify for sales charge reductions if you and certain members of your<br />family invest, or agree to invest in the future, at least $50,000 in MFS Funds.<br />More information about these and other waivers and reductions is available from<br />your financial intermediary and in "Sales Charges and Waivers or Reductions" on<br />page 11 of the fund's prospectus and "Waivers of Sales Charges" on page I-13 of<br />the fund's statement of additional information Part I.</tt>
<div style="display:none">~ http://www.mfs.com/role/OperatingExpensesData_S000038772Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
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.
<div style="display:none">~ http://www.mfs.com/role/ExpenseExampleNoRedemption_S000038772Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
<div style="display:none">~ http://www.mfs.com/role/ShareholderFeesData_S000038772Member column dei_LegalEntityAxis compact * column rr_ProspectusShareClassAxis compact * row primary compact * ~</div>
LFTUX
0.0000
69
729
-0.0242
<tt>R4</tt>
0.0242
0.0000
0.0000
0.0068
0.0310
<tt>Class R4 Shares</tt>
0.0068
<tt>ALL R</tt>
0.0000
LFTTX
0.0000
95
804
-0.0242
<tt>R3</tt>
0.0242
0.0000
0.0025
0.0093
0.0335
<tt>Class R3 Shares</tt>
0.0068
<tt>ALL R</tt>
0.0000
LFTSX
0.0000
120
878
-0.0242
<tt>R2</tt>
0.0242
0.0000
0.0050
0.0118
0.0360
<tt>Class R2 Shares</tt>
0.0068
<tt>ALL R</tt>
0.0000
LFTRX
0.0000
171
1026
-0.0242
<tt>R1</tt>
0.0242
0.0000
0.0100
0.0168
0.0410
<tt>Class R1 Shares</tt>
0.0068
<tt>ALL R</tt>
0.0000
LFTIX
0.0000
69
729
-0.0242
<tt>I</tt>
0.0242
0.0000
0.0000
0.0068
0.0310
<tt>Class I Shares</tt>
0.0068
<tt>I</tt>
0.0000
LFTCX
0.0000
271
171
1026
-0.0242
<tt>C</tt>
0.0242
0.0000
1026
<tt>Class C Shares assuming no redemption at end of period</tt>
0.0100
0.0168
0.0410
<tt>Class C Shares assuming redemption at end of period</tt>
0.0068
<tt>C</tt>
0.0100
LFTBX
0.0000
571
171
1326
-0.0242
<tt>B</tt>
0.0242
0.0000
1026
<tt>Class B Shares assuming no redemption at end of period</tt>
0.0100
0.0168
0.0410
<tt>Class B Shares assuming redemption at end of period</tt>
0.0068
<tt>B</tt>
0.0400
LFTDX
0.0575
664
1333
-0.0242
<tt>A</tt>
0.0242
0.0000
0.0025
0.0093
0.0335
<tt>Class A Shares</tt>
0.0068
<tt>A</tt>
0.0100
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iso4217:USD
pure
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.
Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding management fees, distribution and service fees, interest, taxes, extraordinary expenses, brokerage and transaction costs, investment-related expenses, and fees and expenses associated with investments in investment companies and other similar investment vehicles, such that "Other Expenses" do not exceed 0.00% of the fund's average daily net assets annually for each class of shares. This agreement will continue until at least October 31, 2013, after which Massachusetts Financial Services Company may increase such expense limitation to 0.10% of the fund's average daily net assets annually for each class of shares without a vote of the fund's Board of Trustees. Any increase above 0.10% would require a vote of the fund's Board of Trustees.