<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED FINANCIAL STATEMENTS INCLUDED IN THE FORM 10-Q AND IS QUALIFIED IN
ITS ENTIRETY TO REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>                     <C>
<PERIOD-TYPE>                   12-MOS                   9-MOS                   6-MOS                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1998             DEC-31-1998             DEC-31-1998
<PERIOD-START>                             JAN-01-1998             JAN-01-1998             JAN-01-1998             JAN-01-1998
<PERIOD-END>                               DEC-31-1998             SEP-30-1998             JUN-30-1998             MAR-31-1998
<CASH>                                          35,493                  23,776                  11,516                  83,417
<SECURITIES>                                    47,153                  58,500                  65,229                       0
<RECEIVABLES>                                   75,041                  73,102                  74,788                  70,880
<ALLOWANCES>                                     1,728                   1,541                   1,203                   1,311
<INVENTORY>                                          0                       0                       0                       0
<CURRENT-ASSETS>                               179,016                 176,769                 163,315                 167,633
<PP&E>                                          23,143                  19,742                  17,478                  13,961
<DEPRECIATION>                                   5,909                   4,949                   4,034                   3,259
<TOTAL-ASSETS>                                 217,458                 197,544                 178,607                 180,264
<CURRENT-LIABILITIES>                           48,905                  49,172                  42,192                  48,422
<BONDS>                                              0                       0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                          0                       0                       0                       0
<COMMON>                                           502                     501                     501                     501
<OTHER-SE>                                     158,033                 146,520                 134,421                 129,485
<TOTAL-LIABILITY-AND-EQUITY>                   217,458                 197,544                 178,607                 180,264
<SALES>                                              0                       0                       0                       0
<TOTAL-REVENUES>                               401,371                 285,442                  17,944                  83,749
<CGS>                                          270,790                 191,882                 120,619                  56,882
<TOTAL-COSTS>                                  348,456                 246,671                 155,001                  72,769
<OTHER-EXPENSES>                                 3,470                     516                     258                       0
<LOSS-PROVISION>                                 1,413                     787                     333                       0
<INTEREST-EXPENSE>                                   0                       0                       0                       0
<INCOME-PRETAX>                                 53,015                  37,694                  22,136                  11,653
<INCOME-TAX>                                    20,459                  14,789                   9,294                   4,667
<INCOME-CONTINUING>                             32,556                  22,905                  12,842                   6,986
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                    32,556                  22,905                  12,842                   6,986
<EPS-PRIMARY>                                     0.62                    0.46                    0.26                    0.14
<EPS-DILUTED>                                     0.62                    0.46                    0.26                    0.14
        

</TABLE>