ForewordDrug abuse is the product of an extraordinarily complex interaction between man (the host), his community (the environment), and a variety of psychoactive chemicals (the agents). Epidemiology, the discipline devoted to studying the rates and patterns of disease in the community, is well suited to the analysis of this type of problem. Although many people equate epidemiology with the study of acute communicable disease, in fact the latter is but one specific application of epidemiologic techniques. These techniques-which run the gamut from straightforward demographic characterizations of populations affected by particular problems to complex, prospective cohort studies designed to elucidate the rates and etiologies of particular problems-are applicable to phenomena as diverse as cancer, occupational disease, nutrition, and family planning. Drug abuse is yet another problem to which this methodology can be applied. Although the application of epidemiology to the study of drug abuse is a recent development, epidemiology has a long and distinguished tradition of grappling with serious health problems and producing a clearer understanding of their nature.Because of the social impact of drug abusing behavior and the fear and misunderstanding drug abuse engenders in the public, objective analysis of drug abuse has been hampered by man's preconceived notions, such as "once a heroin addict, always a heroin addict," "drug abuse causes crime," "college campuses are the main focus of drug abuse activity," "heroin users are violent, uncontrollable dope fiends," "the pusher is responsible for enticing innocent victims into using drugs," and "using marijuana