This chapter traces the development of American experimental theatre ensembles from the 1960s to the 2010s. It emphasizes how the values of the 1960s youth culture and Off-Off-Broadway, including egalitarianism and anticommercialism, informed the devising practices of groups such as the Open Theater, the Performance Group, and the San Francisco Mime Troupe. It also addresses how efforts to critique and expand on the work of 1960s ensembles have informed the work of such later groups as Spiderwoman, Split Britches, the SITI Company, Tectonic Theatre Project, Pig Iron Theatre, and the Nature Theatre of Oklahoma. It argues that developments in form and process by American devising ensembles reflect an evolving understanding of theatre’s relationship to the social sphere and to the practice of freedom.