Born in Brooklyn, McCarthy studied nursing and lived with her family in the Long Island town of Mineola, a suburban area near New York City, with her husband, Dennis, and son, Kevin. On December 7, 1993 her husband was killed and her son was injured on a commuter train returning to Mineola, when a gunman opened fire on random passengers. McCarthy responded to the tragedy by launching a campaign against gun violence that eventually propelled her to Congress. McCarthy serves on the Education and Workforce Committee, and the Financial Services Committee. In addition to her efforts to reduce gun violence, McCarthy is especially active in issues relating to education and public health.