<ARTICLE> 6
<CIK> 0000810902
<NAME> BARON ASSET FUND

   <NUMBER> 4
   <NAME> BARON IOPPORTUNITY FUND

                             
<PERIOD-TYPE>                   12-MOS
<FISCAL-YEAR-END>                          SEP-30-2000
<PERIOD-START>                             FEB-29-2000
<PERIOD-END>                               SEP-30-2000
<INVESTMENTS-AT-COST>                      208,136,848
<INVESTMENTS-AT-VALUE>                     189,389,757
<RECEIVABLES>                                5,609,883
<ASSETS-OTHER>                                      87
<OTHER-ITEMS-ASSETS>                                 0
<TOTAL-ASSETS>                             194,999,727
<PAYABLE-FOR-SECURITIES>                     6,529,755
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                      303,343
<TOTAL-LIABILITIES>                          6,833,098
<SENIOR-EQUITY>                                      0
<PAID-IN-CAPITAL-COMMON>                   217,512,959
<SHARES-COMMON-STOCK>                       21,474,230
<SHARES-COMMON-PRIOR>                                0
<ACCUMULATED-NII-CURRENT>                      539,050
<OVERDISTRIBUTION-NII>                               0
<ACCUMULATED-NET-GAINS>                   (11,138,289)
<OVERDISTRIBUTION-GAINS>                             0
<ACCUM-APPREC-OR-DEPREC>                  (18,747,091)
<NET-ASSETS>                               188,166,629
<DIVIDEND-INCOME>                               32,677
<INTEREST-INCOME>                            2,283,177
<OTHER-INCOME>                                       0
<EXPENSES-NET>                               1,776,804
<NET-INVESTMENT-INCOME>                        539,050
<REALIZED-GAINS-CURRENT>                  (11,138,289)
<APPREC-INCREASE-CURRENT>                 (18,747,091)
<NET-CHANGE-FROM-OPS>                     (29,346,330)
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                            0
<DISTRIBUTIONS-OF-GAINS>                             0
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                     25,760,021
<NUMBER-OF-SHARES-REDEEMED>                (4,285,791)
<SHARES-REINVESTED>                                  0
<NET-CHANGE-IN-ASSETS>                     188,166,629
<ACCUMULATED-NII-PRIOR>                              0
<ACCUMULATED-GAINS-PRIOR>                            0
<OVERDISTRIB-NII-PRIOR>                              0
<OVERDIST-NET-GAINS-PRIOR>                           0
<GROSS-ADVISORY-FEES>                        1,184,536
<INTEREST-EXPENSE>                                   0
<GROSS-EXPENSE>                              1,807,923
<AVERAGE-NET-ASSETS>                       202,423,761
<PER-SHARE-NAV-BEGIN>                            10.00
<PER-SHARE-NII>                                   0.03
<PER-SHARE-GAIN-APPREC>                         (1.27)
<PER-SHARE-DIVIDEND>                                 0
<PER-SHARE-DISTRIBUTIONS>                            0
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                               8.76
<EXPENSE-RATIO>                                   .015