Dr. Alan Neaigus is Director of Research in the HIV Epidemiology and Field Services Program at the New York City Department of Health and Mental Hygiene (NYC DOHMH), and an Adjunct Associate Professor in the Department of Epidemiology at Columbia University. Prior to this, he was the Deputy Director of the Institute for International Research on Youth at Risk and a Principal Investigator at National Development and Research Institutes in NYC. At the NYC DOHMH he directs research on risk behaviors and HIV prevalence among at-risk HIV populations, as well as research on the clinical status, service utilization and health behaviors of people living with HIV/AIDS. Over the past several years his research has focused on HIV/AIDS and hepatitis among injecting and non-injecting drug users, and on the relationship of drug users' social and risk networks to their risk of infection with HIV, hepatitis B and hepatitis C. He has also conducted research on the factors associated with the transition to injecting among non-injecting drug users. Dr. Neaigus has studied the relation of drug use to HIV and hepatitis in NYC and in Newark, NJ, as well as among Mexican-American heroin users in San Antonio, Texas. His international work has included studies of HIV and hepatitis risk among drug users in Marseilles, France, and in Budapest, Hungary. He has authored or co-authored numerous publications in peer-reviewed journals, and has delivered many presentations at professional meetings.