A social network is a set of people or institutions (actors) linked by relations and needs; relations and needs determine the structure of a network. Criminal behavior creates multirelational networks, such that SNA can answer significant questions about networks and crime. Regardless of whether the focus is on the larger body or a component of the network, it is important to understand the social networks that link criminals. The current study of drug-selling networks stemmed from a project on violence and criminal networks in St. Louis, MO, which began in the winter of 2001. An analysis of the actors in a homicide sample revealed a set of networks involved in drug-related activity. A durable and thriving drug market relies on a network with relations among the actors that involve divisions of street-level employment. Jobs within the network include lookouts, runners, stash monitors, money collectors, screeners, sellers, and protectors. This study focused on the dynamics of 486 drug-related criminal incidents that involved a network of 860 individuals; 386 of these individuals were active criminals, and the others engaged in activities that involved them in criminal events. This study found that in high-crime, drug-infested neighborhoods, drug selling is based in complex networks that provide jobs and income for those with limited academic education and poor job prospects in legitimate work. Incarceration for nonviolent or minor offenses further embeds them in criminal networks. Upon release, they return to their old neighborhoods and resume the only jobs they have known with the people they know. 3 tables, 7 figures, and 4 references