In this study I examine, from an ethnomusicological perspective, a tradition of avant-garde jazz improvisation, cultivated by a collective association of musicians residing and performing primarily on New York's Lower East Side. Based on ethnographic participant-observation, along with historical inquiry and musicological analysis, I investigate the manner in which the aesthetic practices predominating in this group express the shared musical paradigms, aesthetic commitments, and meta-musical ideals around which this urban community has coalesced. My specific concern is to illustrate how particular modes of musical interaction reflect, inspire, and foster certain models of social organization, whose realization, in turn, creates distinctive types of community structures for the support, transmission, and dissemination of these socio-musical ideals and practices. More generally, I explore the central significance of musical performances in creating, maintaining, and renewing the bonds of subcultural communities through patterned symbolic interaction. Fundamentally an inquiry into the processes by which music becomes meaningful to artists and audiences, this study documents the shifting connotations of an improvisational aesthetic in circulation across social, cultural, and political boundaries.