A Life in the Theatre is one of American playwright David Mamet's early successes. The two-character drama/comedy has hallmarks of Mamet's later work: intense characters; taut, revealing dialogue; and a mentor/teacher relationship. Describing life in the footlights from an actor's point of view, A Life in the Theatre focuses on the relationship between two thespians: Robert, an older, experienced performer; and John, a relative newcomer. Though Robert's guidance is welcomed by John at first, as the play progresses Robert falters as an actor and mentor, and John emerges as a mature actor.

Mamet was inspired to write A Life in the Theatre by what he had observed backstage as well as by his own experiences in his short, unsuccessful career as an actor. A Life in the Theatre made its premiere at the Goodman Theatre in Chicago, Illinois, in February 1977. A slightly different, expanded version of the play debuted in an off-Broadway production in New York City's Theatre de Lys in October 1977.

A Life in the Theatre has been regularly performed around the world since these first productions, and though a few critics vehemently dismissed the play, it has received generally positive review. Many who praise the play share the opinion of Edith Oliver in the New Yorker. Writing about the original New York production, Oliver declared, "Mr. Mamet has written—in gentle ridicule; in jokes, broad and tiny; and in comedy, high and low—a love letter to the theatre. It is quite a feat, and he has pulled it off."