CALVERT SOCIAL INVESTMENT FUND
NSAR-A, 1999-05-25
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<PAGE>      PAGE  1
000 A000000 03/31/99
000 C000000 0000356682
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 3.0
000 J000000 A
001 A000000 CALVERT SOCIAL INVESTMENT FUND
001 B000000 811-3334
001 C000000 3019514881
002 A000000 4550 MONTGOMERY AVE., SUITE 1000N
002 B000000 BETHESDA
002 C000000 MD
002 D010000 20814
003  000000 N
004  000000 N
005  000000 N
006  000000 N
007 A000000 Y
007 B000000  5
007 C010100  1
007 C020100 MONEY MARKET PORTFOLIO
007 C030100 N
007 C010200  2
007 C020200 BALANCED PORTFOLIO
007 C030200 N
007 C010300  3
007 C020300 BOND PORTFOLIO
007 C030300 N
007 C010400  4
007 C020400 EQUITY PORTFOLIO
007 C030400 N
007 C010500  5
007 C020500 MANAGED INDEX PORTFOLIO
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007 C010700  7
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<PAGE>      PAGE  2
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011 A00AA01 CALVERT DISTRIBUTORS, INC.
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<PAGE>      PAGE  3
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<PAGE>      PAGE  4
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<PAGE>      PAGE  5
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<PAGE>      PAGE  6
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<PAGE>      PAGE  7
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<PAGE>      PAGE  8
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<PAGE>      PAGE  9
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<PAGE>      PAGE  10
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<PAGE>      PAGE  11
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<PAGE>      PAGE  12
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<PAGE>      PAGE  13
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<PAGE>      PAGE  14
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<PAGE>      PAGE  15
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<PAGE>      PAGE  16
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<PAGE>      PAGE  17
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<PAGE>      PAGE  18
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<PAGE>      PAGE  20
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<PAGE>      PAGE  21
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<PAGE>      PAGE  22
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<PAGE>      PAGE  24
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083 A000500 N
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085 A000500 Y
085 B000500 N
SIGNATURE   WILLIAM M. TARTIKOFF
TITLE       GENERAL COUNSEL


WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 616
   <NAME> MONEY MARKET PORTFOLIO
<MULTIPLIER> 1000

<S>                             <C>
<PERIOD-TYPE>                   6-MOS
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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUN
<SERIES>
   <NUMBER> 626
   <NAME> BALANCED PORTFOLIO, CLASS A
<MULTIPLIER> 1000

<S>                             <C>
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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 636
   <NAME> BALANCED PORTFOLIO, CLASS B
<MULTIPLIER> 1000

<S>                             <C>
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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 646
   <NAME> BALANCED PORTFOLIO, CLASS C
<MULTIPLIER> 1000

<S>                             <C>
<PERIOD-TYPE>                   6-MOS
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<EXPENSE-RATIO>                                   2.15
[AVG-DEBT-OUTSTANDING]                               0
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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 656
   <NAME> BALANCED PORTFOLIO, CLASS I
<MULTIPLIER> 1000

<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          SEP-30-1998
<PERIOD-START>                             OCT-01-1998
<PERIOD-END>                               MAR-31-1999
<INVESTMENTS-AT-COST>                           666772
<INVESTMENTS-AT-VALUE>                          779927
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<SHARES-COMMON-PRIOR>                                0
<ACCUMULATED-NII-CURRENT>                          (3)
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<EQUALIZATION>                                       0
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<PER-SHARE-DIVIDEND>                           (0.160)
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<PER-SHARE-NAV-END>                             33.360
<EXPENSE-RATIO>                                   0.75
[AVG-DEBT-OUTSTANDING]                               0
[AVG-DEBT-PER-SHARE]                                 0


</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 666
   <NAME> BOND PORTFOLIO, CLASS A
<MULTIPLIER> 1000

<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          SEP-30-1998
<PERIOD-START>                             OCT-01-1998
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<INVESTMENTS-AT-COST>                            71801
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WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
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   <NUMBER> 676
   <NAME> BOND PORTFOLIO, CLASS B
<MULTIPLIER> 1000

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WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

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<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 686
   <NAME> BOND PORTFOLIO, CLASS C
<MULTIPLIER> 1000

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WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
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   <NUMBER> 717
   <NAME> EQUITY PORTFOLIO, CLASS A
<MULTIPLIER> 1000

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WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 727
   <NAME> EQUITY PORTFOLIO, CLASS B
<MULTIPLIER> 1000

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WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 737
   <NAME> EQUITY PORTFOLIO, CLASS C
<MULTIPLIER> 1000

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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 747
   <NAME> MANAGED INDEX PORTFOLIO, CLASS A
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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 757
   <NAME> MANAGED INDEX PORTFOLIO, CLASS B
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</TABLE>
WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUN
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   <NUMBER> 767
   <NAME> MANAGED INDEX PORTFOLIO, CLASS C
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WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.

<TABLE> <S> <C>

<ARTICLE> 6
<CIK> 0000356682
<NAME> CALVERT SOCIAL INVESTMENT FUND
<SERIES>
   <NUMBER> 787
   <NAME> MANAGED INDEX PORTFOLIO, CLASS I
<MULTIPLIER> 1000

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