<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information extracted from financial
statements of Northwestern Mutual Series Fund, Inc. Aggressive Growth Stock
Portfolio June 30, 2000 and is qualified in its entirety by reference to such
financial statements.
</LEGEND>
<SERIES>
<NUMBER> 02
<NAME> AGGRESSIVE GROWTH STOCK PORTFOLIO
<MULTIPLIER> 1000
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-END> JUN-30-2000
<INVESTMENTS-AT-COST> 1154959
<INVESTMENTS-AT-VALUE> 1810674
<RECEIVABLES> 166
<ASSETS-OTHER> 26238
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 1837078
<PAYABLE-FOR-SECURITIES> 8343
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 16623
<TOTAL-LIABILITIES> 24966
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 967829
<SHARES-COMMON-STOCK> 372944
<SHARES-COMMON-PRIOR> 309009
<ACCUMULATED-NII-CURRENT> 529
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 188039
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 655715
<NET-ASSETS> 1812112
<DIVIDEND-INCOME> 619
<INTEREST-INCOME> 4184
<OTHER-INCOME> 0
<EXPENSES-NET> 4274
<NET-INVESTMENT-INCOME> 529
<REALIZED-GAINS-CURRENT> 192367
<APPREC-INCREASE-CURRENT> 42984
<NET-CHANGE-FROM-OPS> 235880
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0
<DISTRIBUTIONS-OF-GAINS> 203984
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 86558
<NUMBER-OF-SHARES-REDEEMED> 68503
<SHARES-REINVESTED> 45880
<NET-CHANGE-IN-ASSETS> 326801
<ACCUMULATED-NII-PRIOR> 0
<ACCUMULATED-GAINS-PRIOR> 199657
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 4264
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 4288
<AVERAGE-NET-ASSETS> 0
<PER-SHARE-NAV-BEGIN> 4.81
<PER-SHARE-NII> 0
<PER-SHARE-GAIN-APPREC> 0.68
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> 0.63
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 4.86
<EXPENSE-RATIO> 0.51
</TABLE>
