Lee Hoffer holds a Masters degree in Anthropology and Ph.D. in Health and Behavioral Sciences from the University of Colorado at Denver. He also holds a Masters degree in Psychiatric Epidemiology from Washington University School of Medicine in St. Louis. Since 1992, Lee has conducted research on numerous National Institute on Drug Abuse's (NIDA) funded research projects that have focused on understanding the political, social and cultural dimensions of HIV risk behaviors of out-of-treatment drug users. From 1997-1999 he was Colorado's representative to NIDA's, Community Epidemiology Workgroup, assembling data and reporting on statewide drug use trends. In 2000, he was awarded a two-year NIDA pre-doctoral fellowship to conduct an ethnographic study of a heroin dealing network, which resulted in Junkie Business. From 2002-2005, Lee trained with Dr. Linda Cottler as a NIDA post-doctoral fellow in psychiatric epidemiology at Washington University School of Medicine in St. Louis. Interested in ethnography and epidemiology, Lee participated in a number of research projects during his fellowship. Currently Lee is a research instructor in the Epidemiology and Prevention Research Group (EPRG) in the department of Psychiatry at Washington University School of Medicine, where, in addition to teaching medical anthropology, he is actively extending his research on the illegal drug economy. Through a two-year grant from NIDA, he is using ethnographic data on heroin dealing to develop several agent-based computer simulation models. Borrowing from Complexity theory and non-linear dynamics, the aim of this project is to elaborate how, through the exchange and distribution of illegal drugs described in Junkie Business, various self-organizing economic and social structures of drug users emerge and operate.