<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
this schedule contains summary financial information extracted from mason street
funds, inc. index 500 stock fund, 03/31/00 financial statements class b.
</LEGEND>
<CIK> 0001023744
<NAME> MASON STREET FUNDS, INC.
<SERIES>
<NUMBER> 012
<NAME> INDEX 500 STOCK FUND CLASS B
<S> <C>
<PERIOD-TYPE> 12-MOS
<FISCAL-YEAR-END> MAR-31-2000
<PERIOD-START> APR-01-1999
<PERIOD-END> MAR-31-2000
<INVESTMENTS-AT-COST> 72847095
<INVESTMENTS-AT-VALUE> 97529787
<RECEIVABLES> 508240
<ASSETS-OTHER> 8255
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 98046282
<PAYABLE-FOR-SECURITIES> 1286
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 127276
<TOTAL-LIABILITIES> 128562
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 72451814
<SHARES-COMMON-STOCK> 1661567
<SHARES-COMMON-PRIOR> 1069488
<ACCUMULATED-NII-CURRENT> 112491
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 303238
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 25050177
<NET-ASSETS> 97917720
<DIVIDEND-INCOME> 1247623
<INTEREST-INCOME> 225519
<OTHER-INCOME> 0
<EXPENSES-NET> 1033111
<NET-INVESTMENT-INCOME> 440031
<REALIZED-GAINS-CURRENT> 13164839
<APPREC-INCREASE-CURRENT> 3119063
<NET-CHANGE-FROM-OPS> 16723933
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 7291554
<DISTRIBUTIONS-OF-GAINS> 441245
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 740906
<NUMBER-OF-SHARES-REDEEMED> 176027
<SHARES-REINVESTED> 27200
<NET-CHANGE-IN-ASSETS> 10081120
<ACCUMULATED-NII-PRIOR> 484221
<ACCUMULATED-GAINS-PRIOR> 10962090
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 187008
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 782019
<AVERAGE-NET-ASSETS> 0
<PER-SHARE-NAV-BEGIN> 16.65
<PER-SHARE-NII> (0.01)
<PER-SHARE-GAIN-APPREC> 2.72
<PER-SHARE-DIVIDEND> 0.05
<PER-SHARE-DISTRIBUTIONS> 0.29
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 19.02
<EXPENSE-RATIO> 1.50
</TABLE>
