Known for transferring her political affiliation from the Republican to the Democratic Party (in 1996), she was elected in 1997 as a New York fourth congressional district representative to the United States Congress.
Before entering politics, she worked as a nurse.
Diagnosed with lung cancer in 2013, she decided in 2014 not to run for re-election.
After her husband and son -- Dennis and Kevin McCarthy -- were killed in a 1993 shooting on a Long Island Railroad train, she became a strong proponent of gun control laws.
She and California Senator Dianne Feinstein co-authored a 2012 gun control bill.