Bernstein’s extrovert personality, ambitions and eclectic talent were perhaps best demonstrated in the theatrical medium, and this chapter explores the origins of Bernstein’s relationship with this medium, looking at the collaborations, contexts, and influences surrounding his first works for the New York stage: the ballet Fancy Free (1944) and the musicals On the Town (1944), Wonderful Town (1953) and Candide (1956). There is a particular focus on Bernstein’s employment of symphonic dance music, the rhythmic vitality contained within many numbers, and his inclusion of both ‘highbrow’ compositional techniques and ‘lowbrow’ sounds of jazz and popular culture within his scores. The author also considers how Bernstein’s music helped to vividly portray the locations and characters within the shows, and discusses the musical elements found in these early works that would later resurface in his contribution to West Side Story.