The middle of five children. His father was a police officer/detective and his mother was a social worker. He received his B.A. from St. Vincent College in Latrobe, Pennsylvania and pursued his M.F.A. on a full scholarship at the Catholic University of America in Washington, D.C. Kelly has appeared in numerous off-Broadway and off-off-Broadway productions, primarily at the Public Theater and the Second Stage. A product of regional national theater, he has been a company member of the Williamstown Theatre Festival, the Folger Theater, Arena Stage, and the Actors Theater of Louisville among others. He toured with the National Players, the oldest classical touring company in the United States. He starred on Broadway as Brick opposite Kathleen Turner in "Cat on a Hot Tin Roof", and as Paul Verrall opposite Madeline Kahn in "Born Yesterday". In 2003, he appeared at the Mark Taper Theater Forum, originating the role of Richard in "Living Out" by Lisa Loomer.
