This essay examines the incorporation of immigrant musicians in a jazz jam session in Brooklyn, New York. Migration scholars define incorporation as a dialectical process in which hosts and immigrants negotiate established social boundaries between "us" and "not us." While the social dynamics of jam sessions have intrigued scholars since the 1950s, the interactions between immigrants and American-born musicians in jazz jam sessions have not been studied. Drawing on ethnographic participation as a bass player in a weekly jam session in Brooklyn, I analyze the ways musical competence is used to establish and negotiate social boundaries between immigrants and hosts. Ultimately, I argue that jam sessions privilege incorporation, allowing immigrant musicians to cross, blur and shift social boundaries between themselves and their American-born peers.