This case study of Tony Sheldon considers how an actor develops versatility in emotional delivery and the capacity to work in all theatre genres. Sheldon is one of Australia's best known and most successful stage actors. He has appeared in Shakespearean drama, cabaret, musical theatre and contemporary plays written by Australian, British and American playwrights. He is one of a sizeable group of Australian actors of his generation to have learned to act 'on the job' with directors and other actors rather than undertaking formal qualifications in an institution or studio. This article examines Sheldon's experience of learning to act, drawing on a life interview with the actor. It considers the opportunities and the difficulties Sheldon experienced in his early career in relation to boundary blurring and self-belief, trauma, directorial rehearsal styles, typecasting, comic acting in partnership and managing one's character in long seasons. The article explores some of the problems that the actor has overcome, the importance of specific directors in his development, and the dynamics of informal training in the context of an overall ecology of theatre over half a century.