O'Connell was born in the South Bronx district of New York, one of five children whose parents were Irish immigrants. When she finished school, she pursued her interest in theatre studying first at Erwin Piscator's Dramatic Workshop, New York, and later at the Actors Studio run by Lee Strasberg. In her early twenties, O'Connell moved to Dublin, Ireland, where she set up the Stanislavski Studio at the Pocket Theatre. There she trained a small company of actors in Stanislavski's system. In 1967, she founded the Focus Theatre, becoming its manager, artistic Director, and fundraiser—as well as acting in many of its productions.
