Penn's first real recognition as a director came from his screen adaptation of the beloved play which he had successfully directed twice on Broadway. For the screen, Penn beautifully captured the tenderness and terror that united Helen Keller and Anne Sullivan, played with great sensitivity and power by Patty Duke and Anne Bancroft, respectively. The Miracle Worker is a key work in Penn's oeuvre, the film that perhaps makes clearest the concern for non-verbal communication and expressive gestures that runs throughout his films.