This handbook examines the scope and ambition of Stephen Sondheim's musicals by drawing on the perspectives of musicological and dramaturgical scholars, literary and film critics, and musical theatre practitioners. Consisting of twenty-seven essays, it analyses Sondheim's radical re-invention of the artistic form of the Broadway musical in response to various traditions of artistic innovation and popular entertainment and how his work with several collaborators has radically transformed the history of American musical theatre.