[3] Broderick attended Manchester Central High School and then took pre-medical courses at the University of New Hampshire for two years.

Director J. Donald Batcheller, faculty advisor to the student drama club (Mask and Dagger), was impressed and gave him the role of Bluntschli, an anti-romantic Swiss soldier.

Broderick took his advice and Kennedy subsequently directed him to the Neighborhood Playhouse, where he gained the necessary experience and training for a successful acting career in both films and television.

[8] Other notable television appearances included the Twilight Zone episode "On Thursday We Leave for Home" and the Public Television productions of Jean Shepherd's The Phantom of the Open Hearth and The Great American Fourth of July and Other Disasters, in which he played Ralph Parker's father, "the Old Man".

His notable film roles include Ray Brock, the complex father figure of a New England commune in Alice's Restaurant (1969), the subway motorman in The Taking of Pelham One Two Three (1974), FBI agent Sheldon in Dog Day Afternoon (1975), and Joe in The Shadow Box (1980) directed by Paul Newman.