[4] A life member of The Actors Studio,[5] Penn won the Theatre World Award in 1954 for his performance in the play The Girl on the Via Flaminia.

On March 3, 1961, he co-starred with Peter Falk and Joyce Van Patten in the episode "Cold Turkey" of the ABC legal drama series The Law and Mr. Jones starring James Whitmore.

Penn landed work as a director for many television series, including I Spy, Lost in Space, Cannon, Star Trek, Blue Light, Custer, the 1976 western Sara, St.

[citation needed] Penn supported the Hollywood trade unions[6] and refused to accuse others to the House Un-American Activities Committee in their investigation of suspected Communist infiltration of the film industry.

[7] He found acting work in television, but CBS ousted him after receiving an anonymous accusation that he had addressed a Communist political meeting.