A major name in American theater, he was renowned for his innovative stagings of plays and musicals by Sam Shepard, Eugene O'Neill, Amiri Baraka.

When Ferencz arrived in New York, he and his first wife, Pamela Mitchell, created the Yogi Bear and Huckleberry Hound Roadshow with Tim and Deirdre McDonald, in association with Scollon Productions.

In the early 1970s, Ferencz directed productions of "Brecht on Brecht" for The All Angel's Players, NYC, Cry of Players (William Gibson), Incident at Vichy (Arthur Miller), Mister Roberts (Thomas Haggen) and Happy End (Bertolt Brecht) for the historic Amateur Comedy Club (in Sniffen Court since 1884), as well as a series of Agatha Christie mysteries for Narrows Community Theater, which Ferencz made popular when he adapted the mysteries to take place in the Bay Ridge community of Brooklyn.

Ferencz's other Off and Off-Off-Broadway credits included Paris Lights (1980), Battery (1981), Money: A Jazz Opera (1982), Harm's Way (1985), Welcome Back to Salamaca (1988), Conjur Woman by Beatrice Manley, and Prague, 1912 (2017).

Regionally, he worked with the San Diego Rep, Berkeley Repertory Theatre, Pittsburgh Public, The Cleveland Playhouse, Syracuse Stage, among others.