<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
this schedule contains summary financial information extracted from mason street
funds, inc. index 500 stock fund, 09/30/00 financial statement class b.
</LEGEND>
<CIK> 0001023744
<NAME> MASON STREET FUNDS, INC.
<SERIES>
<NUMBER> 012
<NAME> INDEX 500 STOCK FUND CLASS B
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> MAR-31-2001
<PERIOD-START> APR-01-2000
<PERIOD-END> SEP-30-2000
<INVESTMENTS-AT-COST> 78,483,930
<INVESTMENTS-AT-VALUE> 98,573,111
<RECEIVABLES> 148,140
<ASSETS-OTHER> 144,042
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 98,865,293
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 7,492,357
<TOTAL-LIABILITIES> 7,492,357
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 69,677,855
<SHARES-COMMON-STOCK> 1,802,887
<SHARES-COMMON-PRIOR> 1,661,567
<ACCUMULATED-NII-CURRENT> 401,784
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 1,341,241
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 19,952,056
<NET-ASSETS> 91,372,936
<DIVIDEND-INCOME> 556,855
<INTEREST-INCOME> 256,836
<OTHER-INCOME> 0
<EXPENSES-NET> (524,398)
<NET-INVESTMENT-INCOME> 289,293
<REALIZED-GAINS-CURRENT> 1,037,449
<APPREC-INCREASE-CURRENT> (5,098,121)
<NET-CHANGE-FROM-OPS> (3,771,379)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 0
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 215,481
<NUMBER-OF-SHARES-REDEEMED> 74,161
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> (6,544,784)
<ACCUMULATED-NII-PRIOR> 112,491
<ACCUMULATED-GAINS-PRIOR> 303,238
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 148,677
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 613,996
<AVERAGE-NET-ASSETS> 32,391,677
<PER-SHARE-NAV-BEGIN> 19.02
<PER-SHARE-NII> 0.02
<PER-SHARE-GAIN-APPREC> (0.77)
<PER-SHARE-DIVIDEND> 0.00
<PER-SHARE-DISTRIBUTIONS> 0.00
<RETURNS-OF-CAPITAL> 0.00
<PER-SHARE-NAV-END> 18.27
<EXPENSE-RATIO> 1.50
</TABLE>
