A field worker was assigned to a heroin distribution site or "copping area" in a Chicago neighborhood for a period of one year. He identified and monitored 127 different dealers and consumers who were regular visitors to the site. Thirty-four of these addicts were involved in a home visit and outreach treatment project. These sources of data permitted the authors to describe the role structure of a local heroin maintenance system, the distribution of its membership in various roles, and the social and treatability characteristics of the occupants of these roles. Their findings suggest that neighborhood heroin distribution systems are amenable to study and manipulation by treatment programs.Abstract Teaser