Abstract
Despite a consensus view that we are experiencing an epidemic of drug and alcohol abuse in adolescents, there is little agreement about the definition of adolescent substance abuse disorders. This review explores past and current efforts at defining psychoactive substance use problems and the relevance of these efforts to adolescents. Current diagnostic classifications and criteria for substance abuse and dependence are often inadequate in describing the clinically relevant patterns of substance use in adolescents. A discussion of future directions in the nosology of adolescent substance abuse focuses on the need for the development of a valid, meaningful classification system for substance use problems, using data from studies of prevalence, natural history, genetics, and treatment outcome among youth.