Introduction Julia Listengarten and Stephen Di Benedetto; Part I. Commercial and Mainstream Theatre: 1. Broadway post-1945 to 1960: shifting perspectives Susan C. W. Abbotson; 2. Bridging the gap: Broadway and the experimental from the 1960s to 2020 Cindy Rosenthal; 3. What's inside? Collaborative relationships at the heart of the American musical Laura MacDonald; 4. Shaping Broadway and off-Broadway plays through collaborations: playwrights, directors, designers, and companies Jessica Silsby Brater; Part II. Regional Theatre Movement: 5. Money matters: dismantling the narrative of the rise of regional theatre Elizabeth A. Osborne; 6. When and where they enter: black and brown voices in American theatre Faedra Chatard Carpenter; 7. El jardín mágico: commissions, collaboration, and new play development in American regional theatre David A. Crespy; Part III. Experimental Theatre and Other Forms of Entertainment: 9. Post-avant-garde theatre Arnold Aronson; 10. Populist provocations and commercial cavalcades: popular entertainments and the rise of mass mediated performance Chase Bringardner.