This chapter argues for an integration of American theater produced across generic and institutional lines during the postwar decades into our understanding of theatrical modernism. It models thinking about theater across traditional divisions of textual drama from non-textual performance, Broadway from Off- and Off-Off-Broadway, and the avant-garde work of the 1960s from what preceded it. Theater in the midcentury was drawn toward both medial specificity and the strategic incorporation of other media, particularly film, and accordingly deployed two key formal strategies: improvisation and citation. Although important to theater in diverse ways before modernism, these became widespread, self-conscious tactics of postwar theater across generic lines, and expanded and developed over the 1950s and 1960s. The chapter closes with a reading of The Living Theatre’s 1959 production of The Connection as an exemplary case study.