Improvisation is the creation and development of new, unexpected, and productive cocreative relations among people. It cultivates the capacity to discern elements of possibility, potential, hope, and promise where none are readily apparent. Improvisers work with the tools they have in the arenas that are open to them. Proceeding without a written score or script, they collaborate to envision and enact something new, to enrich their experience in the world by acting on it and changing it. By analyzing the dynamics of particular artistic improvisations, mostly by contemporary American jazz musicians, the authors reveal improvisation as a viable and urgently needed model for social change. In the process, they rethink politics, music, and the connections between them.