The friendship between Shaw and O’Casey was so personally significant that O’Casey’s widow published an entire book on the subject. This chapter charts the course of that friendship, and examines the influence that Shaw exerted upon O’Casey and vice versa. The chapter begins by examining the way O’Casey knew of Shaw’s work before their first meeting, and traces the contours of their personal relationship after O’Casey moved to London in 1926. The chapter analyses the way that, once the Abbey had rejected The Silver Tassie in 1928, O’Casey turned to Bernard Shaw for friendship and advice, and gives a close reading of the reciprocal influence that can be found in the two men’s playwriting and political viewpoints.