0001105446 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember csisi:C000014080Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:InstitutionalMember 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember rr:AfterTaxesOnDistributionsMember csisi:C000014080Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember rr:AfterTaxesOnDistributionsAndSalesMember csisi:C000014080Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember csisi:C000014081Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember csisi:C000014082Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember csisi:C000118059Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember csisi:CalvertSocialIndexMember 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:RetailMember csisi:LipperMultiCapCoreFundsAvgMember 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:InstitutionalMember csisi:C000014083Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:InstitutionalMember rr:AfterTaxesOnDistributionsMember csisi:C000014083Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:InstitutionalMember rr:AfterTaxesOnDistributionsAndSalesMember csisi:C000014083Member 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:InstitutionalMember csisi:CalvertSocialIndexMember 2012-02-01 2013-01-31 0001105446 csisi:S000005145Member csisi:InstitutionalMember csisi:LipperMultiCapCoreFundsAvgMember 2012-02-01 2013-01-31 pure iso4217:USD 485BPOS 0001105446 CALVERT SOCIAL INDEX SERIES INC 2013-01-30 2013-01-31 2013-01-31 false 2012-09-30 <b>CALVERT SOCIAL INDEX FUND</b><br/><b>Class</b> (Ticker):   <b>A</b> (CSXAX)   <b>B</b> (CSXBX)   <b>C</b> (CSXCX)   <b>Y</b> (CISYX) <b>INVESTMENT OBJECTIVE</b> The Fund seeks to match the performance of the Calvert Social Index®, which measures the investment return of large- and mid-capitalization stocks. This objective may be changed by the Fund's Board of Directors without shareholder approval. <b>FEES AND EXPENSES OF THE FUND </b> This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”). <b>Shareholder Fees</b> (fees paid directly from your investment) <b>Annual Fund Operating Expenses </b>(expenses that you pay<br/>each year as a % of the value of your investment) <b>Example </b> This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that: <ul type="square"><li>you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;</li></ul> <ul type="square"><li>your investment has a 5% return each year; </li></ul> <ul type="square"><li>the Fund’s operating expenses remain the same; and</li></ul> <ul type="square"><li>any Calvert expense limitation is in effect for the period indicated in the fee table above.</li></ul>Although your actual costs may be higher or lower, under these assumptions your costs would be: <b>Portfolio Turnover </b> The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 7% of its portfolio’s average value. <a name="page_16"></a> <b>INVESTMENTS, RISKS AND PERFORMANCE</b><br/><br/><b>Principal Investment Strategies</b> The Fund employs a passive management strategy designed to track, as closely as possible, the performance of the Calvert Social Index. The Fund uses a replication index method, investing in the common stock of each company in the Index in about the same proportion as represented in the Index itself. The Fund will normally invest at least 95% of its net assets, including borrowings for investment purposes, in securities contained in the Index. The Fund will provide shareholders with at least 60 days’ notice before changing this policy. <br /><br /> Calvert Social Index. The Calvert Social Index measures the performance of those companies that meet the sustainable and socially responsible investment criteria and that are selected from the universe of approximately the 1,000 largest U.S. companies, based on total market capitalization, included in the Dow Jones Total Market Index (the “Dow Jones TMI”). The Dow Jones TMI represents the top 95% of U.S. companies based on float-adjusted market capitalization, excluding the very smallest and least-liquid stocks. As of December 31, 2012, the market capitalization of the Calvert Social Index companies ranged from $838 million to $500 billion, with a weighted median level of $38.3 billion and a weighted average level of $94.2 billion. The Fund seeks to have a weighted average capitalization that approximates that of the Index. As of December 31, 2012, there were 675 companies in the Index, though this number will change over time due to company mergers or changes due to Calvert’s evaluation of an issuer’s conduct relative to the sustainable and socially responsible investment criteria. The Index is reconstituted once a year based on an updated list of the 1,000 largest U.S. companies. The Index is also reviewed quarterly to adjust for sustainable and socially responsible investment criteria and other factors. <br /><br /> Sustainable and Socially Responsible Investing. The Fund’s sustainable and socially responsible investment criteria are described in this Prospectus under “About Sustainable and Socially Responsible Investing.” Calvert continuously evaluates the performance of companies included in the Calvert Social Index to ensure compliance with these criteria. <b>Principal Risks </b> You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. 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 government agency. <br /><br /> Index Tracking Risk. An index fund has operating expenses; a market index does not. Although expected to track its target index as closely as possible while satisfying its investment criteria, including financial, sustainability and social responsibility factors, the Fund will not be able to match the performance of the index exactly. <br /><br /> Stock Market Risk. The market prices of stocks held by the Fund may fall. <br /><br /> Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being. <br /><br /> Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion. <br /><br /> Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies. <b>Performance </b> The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average. <br /><br /> The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com. <br /><br /> Performance results for Class Y shares prior to July 13, 2012 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y, unlike Class A, has no Rule 12b-1 fees. <br /><br /> The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return. <b>Calendar Year Total Returns for Class A at NAV</b> The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.<br/><br/>After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary. <b>Average Annual Total Returns<br/>(as of 12/31/12) (with maximum<br/>sales charge deducted)</b> 0.2956 0.0774 0.0307 0.1138 0.0265 -0.4004 0.3411 0.1323 -0.0051 0.1705 <b>CALVERT SOCIAL INDEX FUND<br/>Class </b>(Ticker):   <b>I </b>(CISIX) <b>INVESTMENT OBJECTIVE </b> The Fund seeks to match the performance of the Calvert Social Index<sup>®</sup>, which measures the investment return of large- and mid-capitalization stocks. This objective may be changed by the Fund’s Board of Directors without shareholder approval. 0.1152 0.1134 0.0774 0.109 <b>FEES AND EXPENSES OF THE FUND</b> 0.1502 0.1713 0.18 0.1509 0.0019 This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. 0.0004 0.0014 -0.0002 0.0019 0.0119 0.0244 0.0098 0.0521 0.0506 0.0454 0.0468 0.0469 0.0573 0.0677 0.0742 548 678 278 61 777 580 1082 248 <b>Shareholder Fees </b>(fees paid directly from your investment) 1024 1413 1008 451 1732 2200 2349 1037 -0.02 0 0 0 0.05 0.01 0 0.0475 0 -0.02 -0.02 -0.02 -0.02 <b>Annual Fund Operating Expenses </b>(expenses that you pay each year as a<br/>% of the value of your investment) 0.004 0.004 0.004 0.004 0.0025 0.01 0.01 0 0.0046 0.0098 0.0049 0.0046 0.0111 0.0238 0.0189 0.0086 -0.0036 -0.0063 -0.0014 -0.0026 0.0075 0.0175 0.0175 0.006 0.003 0 0.0021 0.0051 -0.003 0.0021 178 178 682 580 1213 1008 2349 2200 <table style="WIDTH: 6in; FONT-FAMILY: 'Times New Roman'; FONT-SIZE: 11pt" border="0" cellspacing="0"><tr valign="bottom"> <td align="left"> </td> <td style="TEXT-INDENT: 0.225pt" align="right"><b>Quarter</b></td> <td align="right"><b>Total</b></td> <td align="left"> </td></tr> <tr valign="bottom"> <td align="left"> </td> <td style="BORDER-BOTTOM: #000000 1px solid" align="right"><b>Ended</b></td> <td style="BORDER-BOTTOM: #000000 1px solid; TEXT-INDENT: 2.438pt" align="right"><b>Return</b></td> <td style="BORDER-BOTTOM: #000000 1px solid" align="left"> </td></tr> <tr valign="bottom"> <td align="left">Best Quarter (of periods shown)</td> <td align="right">6/30/09</td> <td align="right">18.19</td> <td align="left">%</td></tr> <tr valign="bottom"> <td align="left">Worst Quarter (of periods shown)</td> <td align="right">12/31/08</td> <td align="right">-25.52</td> <td align="left">%</td></tr></table> <b>Example </b> This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:<ul type="square"><li>you invest $1,000,000 in the Fund for the time periods indicated;</li><li> your investment has a 5% return each year;</li><li>the Fund’s operating expenses remain the same; and </li><li>any Calvert expense limitation is in effect for the period indicated in the fee table above.</li></ul>Although your actual costs may be higher or lower, under these assumptions your costs would be: January 31, 2016 2150 6765 19035 54867 <b>Portfolio Turnover</b> The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 7% of its portfolio’s average value. <b>INVESTMENTS, RISKS AND PERFORMANCE<br/><br/>Principal Investment Strategies</b> The Fund employs a passive management strategy designed to track, as closely as possible, the performance of the Calvert Social Index. The Fund uses a replication index method, investing in the common stock of each company in the Index in about the same proportion as represented in the Index itself. The Fund will normally invest at least 95% of its net assets, including borrowings for investment purposes, in securities contained in the Index. The Fund will provide shareholders with at least 60 days’ notice before changing this policy.<br/><br/>Calvert Social Index. The Calvert Social Index measures the performance of those companies that meet the sustainable and socially responsible investment criteria and that are selected from the universe of approximately the 1,000 largest U.S. companies, based on total market capitalization, included in the Dow Jones Total Market Index (the “Dow Jones TMI”). The Dow Jones TMI represents the top 95% of U.S. companies based on float-adjusted market capitalization, excluding the very smallest and least-liquid stocks. As of December 31, 2012, the market capitalization of the Calvert Social Index companies ranged from $838 million to $500 billion, with a weighted median level of $38.3 billion and a weighted average level of $94.2 billion. The Fund seeks to have a weighted average capitalization that approximates that of the Index. As of December 31, 2012, there were 675 companies in the Index, though this number will change over time due to company mergers or changes due to Calvert’s evaluation of an issuer’s conduct relative to the sustainable and socially responsible investment criteria. The Index is reconstituted once a year based on an updated list of the 1,000 largest U.S. companies. The Index is also reviewed quarterly to adjust for sustainable and socially responsible investment criteria and other factors.<br/><br/>Sustainable and Socially Responsible Investing. The Fund’s sustainable and socially responsible investment criteria are described in this Prospectus under “About Sustainable and Socially Responsible Investing.” Calvert continuously evaluates the performance of companies included in the Calvert Social Index to ensure compliance with these criteria. <b>Principal Risks</b> You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. 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 government agency.<br/><br/>Index Tracking Risk. An index fund has operating expenses; a market index does not. Although expected to track its target index as closely as possible while satisfying its investment criteria, including financial, sustainability and social responsibility factors, the Fund will not be able to match the performance of the index exactly.<br/><br/>Stock Market Risk. The market prices of stocks held by the Fund may fall.<br/><br/>Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.<br/><br/>Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.<br/><br/>Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies. You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. 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 government agency. <b>Performance</b> The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.<br/><br/>The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com. The bar chart shows how the performance of the Class I shares has varied from year to year. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. www.calvert.com 0.3016 0.0813 0.035 0.1194 0.0323 -0.3969 0.3484 0.1373 0.0005 0.1771 <table style="WIDTH: 6in; FONT-FAMILY: 'Times New Roman'; FONT-SIZE: 11pt" border="0" cellspacing="0"><tr valign="bottom"> <td align="left"> </td> <td style="TEXT-INDENT: 0.225pt" align="right"><b>Quarter</b></td> <td align="right"><b>Total</b></td> <td align="left"> </td></tr> <tr valign="bottom"> <td align="left"> </td> <td style="BORDER-BOTTOM: #000000 1px solid" align="right"><b>Ended</b></td> <td style="BORDER-BOTTOM: #000000 1px solid; TEXT-INDENT: 2.438pt" align="right"><b>Return</b></td> <td style="BORDER-BOTTOM: #000000 1px solid" align="left"> </td></tr> <tr valign="bottom"> <td align="left">Best Quarter (of periods shown)</td> <td align="right">6/30/09</td> <td align="right">18.39</td><td align="left">%</td></tr> <tr valign="bottom"> <td align="left">Worst Quarter (of periods shown)</td> <td align="right">12/31/08</td> <td align="right">-25.36</td> <td align="left">%</td></tr></table> Best Quarter (of periods shown) 2009-06-30 0.1839 Worst Quarter (of periods shown) 2008-12-31 -0.2536 After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. <b>Average Annual Total Returns<br/>(as of 12/31/12)</b> 0.1771 0.1748 0.1182 0.18 0.1509 0.0172 0.0149 0.0143 0.0244 0.0098 0.0625 0.0603 0.0546 0.0677 0.0742 January 31, 2014 0.07 You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. 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 government agency. The bar chart shows how the performance of the Class A shares has varied from year to year. www.calvert.com The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. 0.07 The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary. Best Quarter (of periods shown) 2009-06-30 0.1819 Worst Quarter (of periods shown) 2008-12-31 -0.2552 <b>Calendar Year Total Returns</b> <div style="display:none">~ http://www.calvert.com/role/ScheduleShareholderFeesCalvertSocialIndexFund column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleAnnualFundOperatingExpensesCalvertSocialIndexFund column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleExpenseExampleTransposedCalvertSocialIndexFund column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleExpenseExampleNoRedemptionTransposedCalvertSocialIndexFund column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleAnnualTotalReturnsCalvertSocialIndexFundBarChart column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleShareholderFeesCalvertSocialIndexFundClassI column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleAnnualFundOperatingExpensesCalvertSocialIndexFundClassI column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleAverageAnnualTotalReturnsTransposedCalvertSocialIndexFund column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleExpenseExampleTransposedCalvertSocialIndexFundClassI column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleAnnualTotalReturnsCalvertSocialIndexFundClassIBarChart column period compact * ~</div> <div style="display:none">~ http://www.calvert.com/role/ScheduleAverageAnnualTotalReturnsTransposedCalvertSocialIndexFundClassI column period compact * ~</div> 50000 The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. The contingent deferred sales charge reduces over time. The investment advisor has agreed to contractually limit direct net annual fund operating expenses to 0.21% through January 31, 2016. Only the Board of Directors of the Fund may terminate the Fund's expense limitation before the contractual period expires. The contingent deferred sales charge reduces over time. The investment advisor has agreed to contractually limit direct net annual fund operating expenses through January 31, 2014. Direct net operating expenses will not exceed 0.75% for Class A, 1.75% for Class B, 1.75% for Class C, and 0.60% for Class Y. Only the Board of Directors of the Fund may terminate the Fund's expense limitation before the contractual period expires.