<ARTICLE> UT
<LEGEND>
This schedule contains summary financial information extracted from the
balance sheet, statement of income and statement of cash flows contained in
Form 10-Q of Commonwealth Energy System for the three months ended March 31,
1999 and is qualified in its entirety by reference to such financial
statements.
</LEGEND>
<CIK> 0000071304
<NAME> COMMONWEALTH ENERGY SYSTEM
<MULTIPLIER> 1,000
       
                            
<FISCAL-YEAR-END>              DEC-31-1999
<PERIOD-END>                   MAR-31-1999
<PERIOD-TYPE>                        3-MOS
<BOOK-VALUE>                      PER-BOOK
<TOTAL-NET-UTILITY-PLANT>        1,017,467
<OTHER-PROPERTY-AND-INVEST>         13,919
<TOTAL-CURRENT-ASSETS>             305,435
<TOTAL-DEFERRED-CHARGES>           265,597
<OTHER-ASSETS>                     173,056
<TOTAL-ASSETS>                   1,775,474
<COMMON>                            43,081
<CAPITAL-SURPLUS-PAID-IN>          112,210
<RETAINED-EARNINGS>                306,645
<TOTAL-COMMON-STOCKHOLDERS-EQ>     461,936
<PREFERRED-MANDATORY>               11,350
<PREFERRED>                              0
<LONG-TERM-DEBT-NET>               384,555
<SHORT-TERM-NOTES>                   7,825
<LONG-TERM-NOTES-PAYABLE>                0
<COMMERCIAL-PAPER-OBLIGATIONS>           0
<LONG-TERM-DEBT-CURRENT-PORT>       46,178
<PREFERRED-STOCK-CURRENT>              820
<CAPITAL-LEASE-OBLIGATIONS>         10,795
<LEASES-CURRENT>                     1,258
<OTHER-ITEMS-CAPITAL-AND-LIAB>     850,757
<TOT-CAPITALIZATION-AND-LIAB>    1,775,474
<GROSS-OPERATING-REVENUE>          269,669
<INCOME-TAX-EXPENSE>                15,348
<OTHER-OPERATING-EXPENSES>         222,872
<TOTAL-OPERATING-EXPENSES>         238,220
<OPERATING-INCOME-LOSS>             31,449
<OTHER-INCOME-NET>                     609
<INCOME-BEFORE-INTEREST-EXPEN>      32,058
<TOTAL-INTEREST-EXPENSE>            10,579
<NET-INCOME>                        21,479
<PREFERRED-STOCK-DIVIDENDS>            222
<EARNINGS-AVAILABLE-FOR-COMM>       21,257
<COMMON-STOCK-DIVIDENDS>             8,954
<TOTAL-INTEREST-ON-BONDS>            8,578
<CASH-FLOW-OPERATIONS>              35,646
<EPS-PRIMARY>                          .99
<EPS-DILUTED>                          .99