The National Institute on Drug Abuse (NIDA) has sponsored a comprehensive research program in response to the dynamic nature of the co-occurring epidemics of drug abuse and HIV/AIDS. This research has yielded a set of scientifically based principles for the use of community planners, policymakers, service providers, and medical practitioners as they develop and implement programs to prevent the spread of HIV and other infections among injecting and non-injecting drug users and their sexual partners.