<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,
1998 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-31-1998
<PERIOD-END>                   MAR-31-1998
<PERIOD-TYPE>                        3-MOS
<BOOK-VALUE>                      PER-BOOK
<TOTAL-NET-UTILITY-PLANT>        1,028,500
<OTHER-PROPERTY-AND-INVEST>         14,040
<TOTAL-CURRENT-ASSETS>             193,616
<TOTAL-DEFERRED-CHARGES>           215,630
<OTHER-ASSETS>                      13,906
<TOTAL-ASSETS>                   1,464,692
<COMMON>                            43,063
<CAPITAL-SURPLUS-PAID-IN>          111,996
<RETAINED-EARNINGS>                292,385
<TOTAL-COMMON-STOCKHOLDERS-EQ>     447,444
<PREFERRED-MANDATORY>               12,140
<PREFERRED>                              0
<LONG-TERM-DEBT-NET>               353,262
<SHORT-TERM-NOTES>                  74,925
<LONG-TERM-NOTES-PAYABLE>                0
<COMMERCIAL-PAPER-OBLIGATIONS>           0
<LONG-TERM-DEBT-CURRENT-PORT>       36,653
<PREFERRED-STOCK-CURRENT>              820
<CAPITAL-LEASE-OBLIGATIONS>         11,530
<LEASES-CURRENT>                     1,376
<OTHER-ITEMS-CAPITAL-AND-LIAB>     526,542
<TOT-CAPITALIZATION-AND-LIAB>    1,464,692
<GROSS-OPERATING-REVENUE>          276,604
<INCOME-TAX-EXPENSE>                16,106
<OTHER-OPERATING-EXPENSES>         225,444
<TOTAL-OPERATING-EXPENSES>         241,550
<OPERATING-INCOME-LOSS>             35,054
<OTHER-INCOME-NET>                     695
<INCOME-BEFORE-INTEREST-EXPEN>      35,749
<TOTAL-INTEREST-EXPENSE>            10,190
<NET-INCOME>                        25,559
<PREFERRED-STOCK-DIVIDENDS>            237
<EARNINGS-AVAILABLE-FOR-COMM>       25,322
<COMMON-STOCK-DIVIDENDS>             8,732
<TOTAL-INTEREST-ON-BONDS>            8,517
<CASH-FLOW-OPERATIONS>              41,122
<EPS-PRIMARY>                         1.18
<EPS-DILUTED>                         1.18