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<SHARES-REINVESTED> 0<F1>
<NET-CHANGE-IN-ASSETS> 218265615
<ACCUMULATED-NII-PRIOR> 287904
<ACCUMULATED-GAINS-PRIOR> 7113445
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 763381
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1194296
<AVERAGE-NET-ASSETS> 5624753<F1>
<PER-SHARE-NAV-BEGIN> 7.13<F1>
<PER-SHARE-NII> 0<F1>
<PER-SHARE-GAIN-APPREC> 2.50<F1>
<PER-SHARE-DIVIDEND> 0<F1>
<PER-SHARE-DISTRIBUTIONS> 0<F1>
<RETURNS-OF-CAPITAL> 0<F1>
<PER-SHARE-NAV-END> 9.63<F1>
<EXPENSE-RATIO> 1.34<F1>
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
<FN>
<F1>SELECT SHARES
</FN>
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<SERIES>
<NUMBER> 013
<NAME> BARR ROSENBERG SERIES TRUST, U.S. SMALL CAPITALIZATION SERIES
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> MAR-31-1998
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 254967520
<INVESTMENTS-AT-VALUE> 305705092
<RECEIVABLES> 4147191
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 52646
<TOTAL-ASSETS> 309904929
<PAYABLE-FOR-SECURITIES> 6209551
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 731065
<TOTAL-LIABILITIES> 6940616
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 234341779
<SHARES-COMMON-STOCK> 1256782<F1>
<SHARES-COMMON-PRIOR> 29170<F1>
<ACCUMULATED-NII-CURRENT> 436477
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 17448485
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 50737572
<NET-ASSETS> 302964313
<DIVIDEND-INCOME> 969245
<INTEREST-INCOME> 192775
<OTHER-INCOME> 33027
<EXPENSES-NET> 974723
<NET-INVESTMENT-INCOME> 220324
<REALIZED-GAINS-CURRENT> 7213034
<APPREC-INCREASE-CURRENT> 45199221
<NET-CHANGE-FROM-OPS> 52632579
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0<F1>
<DISTRIBUTIONS-OF-GAINS> 0<F1>
<DISTRIBUTIONS-OTHER> 0<F1>
<NUMBER-OF-SHARES-SOLD> 1274031<F1>
<NUMBER-OF-SHARES-REDEEMED> 46419<F1>
<SHARES-REINVESTED> 0<F1>
<NET-CHANGE-IN-ASSETS> 218265615
<ACCUMULATED-NII-PRIOR> 287904
<ACCUMULATED-GAINS-PRIOR> 7113445
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 763381
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 1194296
<AVERAGE-NET-ASSETS> 3383056<F1>
<PER-SHARE-NAV-BEGIN> 7.14<F1>
<PER-SHARE-NII> 0<F1>
<PER-SHARE-GAIN-APPREC> 2.50<F1>
<PER-SHARE-DIVIDEND> 0<F1>
<PER-SHARE-DISTRIBUTIONS> 0<F1>
<RETURNS-OF-CAPITAL> 0<F1>
<PER-SHARE-NAV-END> 9.64<F1>
<EXPENSE-RATIO> 1.39<F1>
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
<FN>
<F1>ADVISER SHARES
</FN>
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<SERIES>
<NUMBER> 021
<NAME> BARR ROSENBERG SERIES TRUST, JAPAN SERIES
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> MAR-31-1998
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 1289102
<INVESTMENTS-AT-VALUE> 1064350
<RECEIVABLES> 70175
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 13974
<TOTAL-ASSETS> 1148499
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 82932
<TOTAL-LIABILITIES> 82932
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1811967
<SHARES-COMMON-STOCK> 176614<F1>
<SHARES-COMMON-PRIOR> 162666<F1>
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 72653
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 449002
<ACCUM-APPREC-OR-DEPREC> (224745)
<NET-ASSETS> 1065567
<DIVIDEND-INCOME> 4216
<INTEREST-INCOME> 0
<OTHER-INCOME> 0
<EXPENSES-NET> 8905
<NET-INVESTMENT-INCOME> (4689)
<REALIZED-GAINS-CURRENT> (53108)
<APPREC-INCREASE-CURRENT> 3172
<NET-CHANGE-FROM-OPS> (54625)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0<F1>
<DISTRIBUTIONS-OF-GAINS> 0<F1>
<DISTRIBUTIONS-OTHER> 0<F1>
<NUMBER-OF-SHARES-SOLD> 13948<F1>
<NUMBER-OF-SHARES-REDEEMED> 0<F1>
<SHARES-REINVESTED> 0<F1>
<NET-CHANGE-IN-ASSETS> 43589
<ACCUMULATED-NII-PRIOR> 1523
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 449056
<GROSS-ADVISORY-FEES> 5938
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 136422
<AVERAGE-NET-ASSETS> 1162754<F1>
<PER-SHARE-NAV-BEGIN> 6.20<F1>
<PER-SHARE-NII> (.03)<F1>
<PER-SHARE-GAIN-APPREC> (.25)<F1>
<PER-SHARE-DIVIDEND> 0<F1>
<PER-SHARE-DISTRIBUTIONS> 0<F1>
<RETURNS-OF-CAPITAL> 0<F1>
<PER-SHARE-NAV-END> 5.92<F1>
<EXPENSE-RATIO> 1.50<F1>
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
<FN>
<F1>INSTITUTIONAL SHARES
</FN>
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<SERIES>
<NUMBER> 022
<NAME> BARR ROSENBERG SERIES TRUST, JAPAN SERIES
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> MAR-31-1998
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 1289102
<INVESTMENTS-AT-VALUE> 1064350
<RECEIVABLES> 70175
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 13974
<TOTAL-ASSETS> 1148499
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 82932
<TOTAL-LIABILITIES> 82932
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 1811967
<SHARES-COMMON-STOCK> 3266<F1>
<SHARES-COMMON-PRIOR> 2048<F1>
<ACCUMULATED-NII-CURRENT> 0
<OVERDISTRIBUTION-NII> 72653
<ACCUMULATED-NET-GAINS> 0
<OVERDISTRIBUTION-GAINS> 449002
<ACCUM-APPREC-OR-DEPREC> (224745)
<NET-ASSETS> 1065567
<DIVIDEND-INCOME> 4216
<INTEREST-INCOME> 0
<OTHER-INCOME> 0
<EXPENSES-NET> 8905
<NET-INVESTMENT-INCOME> (4689)
<REALIZED-GAINS-CURRENT> (53108)
<APPREC-INCREASE-CURRENT> 3172
<NET-CHANGE-FROM-OPS> (54625)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0<F1>
<DISTRIBUTIONS-OF-GAINS> 0<F1>
<DISTRIBUTIONS-OTHER> 0<F1>
<NUMBER-OF-SHARES-SOLD> 1665<F1>
<NUMBER-OF-SHARES-REDEEMED> 447<F1>
<SHARES-REINVESTED> 0<F1>
<NET-CHANGE-IN-ASSETS> 43589
<ACCUMULATED-NII-PRIOR> 1523
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 449056
<GROSS-ADVISORY-FEES> 5938
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 136422
<AVERAGE-NET-ASSETS> 21614<F1>
<PER-SHARE-NAV-BEGIN> 6.20<F1>
<PER-SHARE-NII> (.03)<F1>
<PER-SHARE-GAIN-APPREC> (.25)<F1>
<PER-SHARE-DIVIDEND> 0<F1>
<PER-SHARE-DISTRIBUTIONS> 0<F1>
<RETURNS-OF-CAPITAL> 0<F1>
<PER-SHARE-NAV-END> 5.92<F1>
<EXPENSE-RATIO> 1.61<F1>
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
<FN>
<F1>SELECT SHARES
</FN>
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<SERIES>
<NUMBER> 031
<NAME> BARR ROSENBERG SERIES TRUST, INTERNATIONAL SMALL CAPITALIZATION SERIES
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> MAR-31-1998
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 27285882
<INVESTMENTS-AT-VALUE> 26355141
<RECEIVABLES> 902462
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 2298589
<TOTAL-ASSETS> 29556192
<PAYABLE-FOR-SECURITIES> 1732010
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 467317
<TOTAL-LIABILITIES> 2199327
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 27620197
<SHARES-COMMON-STOCK> 2647879<F1>
<SHARES-COMMON-PRIOR> 1269278<F1>
<ACCUMULATED-NII-CURRENT> 108075
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 544175
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (915582)
<NET-ASSETS> 27356865
<DIVIDEND-INCOME> 286443
<INTEREST-INCOME> 0
<OTHER-INCOME> 0
<EXPENSES-NET> 151425
<NET-INVESTMENT-INCOME> 135018
<REALIZED-GAINS-CURRENT> 509221
<APPREC-INCREASE-CURRENT> (955486)
<NET-CHANGE-FROM-OPS> (311247)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0<F1>
<DISTRIBUTIONS-OF-GAINS> 0<F1>
<DISTRIBUTIONS-OTHER> 0<F1>
<NUMBER-OF-SHARES-SOLD> 1418440<F1>
<NUMBER-OF-SHARES-REDEEMED> 39839<F1>
<SHARES-REINVESTED> 0<F1>
<NET-CHANGE-IN-ASSETS> 14312780
<ACCUMULATED-NII-PRIOR> 18047
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 3804
<GROSS-ADVISORY-FEES> 96372
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 263242
<AVERAGE-NET-ASSETS> 18580755<F1>
<PER-SHARE-NAV-BEGIN> 10.13<F1>
<PER-SHARE-NII> .05<F1>
<PER-SHARE-GAIN-APPREC> (.05)<F1>
<PER-SHARE-DIVIDEND> 0<F1>
<PER-SHARE-DISTRIBUTIONS> 0<F1>
<RETURNS-OF-CAPITAL> 0<F1>
<PER-SHARE-NAV-END> 10.13<F1>
<EXPENSE-RATIO> 1.49<F1>
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
<FN>
<F1>INSTITUTIONAL SHARES
</FN>
</TABLE>
<TABLE> <S> <C>
<ARTICLE> 6
<SERIES>
<NUMBER> 032
<NAME> BARR ROSENBERG SERIES TRUST, INTERNATIONAL SMALL CAPITALIZATION SERIES
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> MAR-31-1998
<PERIOD-END> SEP-30-1997
<INVESTMENTS-AT-COST> 27285882
<INVESTMENTS-AT-VALUE> 26355141
<RECEIVABLES> 902462
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 2298589
<TOTAL-ASSETS> 29556192
<PAYABLE-FOR-SECURITIES> 1732010
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 467317
<TOTAL-LIABILITIES> 2199327
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 27620197
<SHARES-COMMON-STOCK> 52364<F1>
<SHARES-COMMON-PRIOR> 18227<F1>
<ACCUMULATED-NII-CURRENT> 108075
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 544175
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> (915582)
<NET-ASSETS> 27356865
<DIVIDEND-INCOME> 286443
<INTEREST-INCOME> 0
<OTHER-INCOME> 0
<EXPENSES-NET> 151425
<NET-INVESTMENT-INCOME> 135018
<REALIZED-GAINS-CURRENT> 509221
<APPREC-INCREASE-CURRENT> (955486)
<NET-CHANGE-FROM-OPS> (311247)
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 0<F1>
<DISTRIBUTIONS-OF-GAINS> 0<F1>
<DISTRIBUTIONS-OTHER> 0<F1>
<NUMBER-OF-SHARES-SOLD> 41861<F1>
<NUMBER-OF-SHARES-REDEEMED> 7724<F1>
<SHARES-REINVESTED> 0<F1>
<NET-CHANGE-IN-ASSETS> 14312780
<ACCUMULATED-NII-PRIOR> 18047
<ACCUMULATED-GAINS-PRIOR> 0
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 3804
<GROSS-ADVISORY-FEES> 96372
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 263242
<AVERAGE-NET-ASSETS> 341025<F1>
<PER-SHARE-NAV-BEGIN> 10.13<F1>
<PER-SHARE-NII> .05<F1>
<PER-SHARE-GAIN-APPREC> (.05)<F1>
<PER-SHARE-DIVIDEND> 0<F1>
<PER-SHARE-DISTRIBUTIONS> 0<F1>
<RETURNS-OF-CAPITAL> 0<F1>
<PER-SHARE-NAV-END> 10.13<F1>
<EXPENSE-RATIO> 1.67<F1>
<AVG-DEBT-OUTSTANDING> 0
<AVG-DEBT-PER-SHARE> 0
<FN>
<F1>SELECT SHARES
</FN>
</TABLE>
