Mary McDonnell was born in April 1952 in Wilkes-Barre, Pennsylvania, USA, and raised in Ithica, New York state, and attended Fredonia State University. Following her gaduating, she attended drama school and joined the East Coast's presdigious Long Wharf Theatre Company, with whom she worked for over 20 years. In 1981, she received an Obie award for her performance in Emily Mann's Still Life. Her other stage credits include the New York premieres of John Patrick Shanley's Savage in Limbo, John O'Keefe's All Night Long, Michael Cristofer's Black Angel, Kathleen Tolan's A Weekend Near Madison, Paula Cizmar's Death of a Miner and Dennis McIntyre's National Anthem, which premiered at the Long Wharf Theatre starring McDonnell and Tom Berenger.