The author argues that before drug abuse can be prevented one must understand why people use drugs. Researchers indicate that drug use progresses in predictable order, from 'gateway drugs' such as tobacco, alcohol, and marijuana, before they use cocaine, PCP, and heroin. Television portrayals of drug use and belief by adolescents of its popularity is another predictor of who will use drugs. Drug use by close friends is described as the 'single best predictor' of who will experiment with drugs. Rebelliousness, risk-taking, striving for independence, and parental qualities also are predictors of drug use. Among the drug abuse prevention approaches discussed are peer pressure, resistance training, normative education to counter perceptions of prevalence and approval, and critical analysis skills to counter the influence of mass media messages. Others include how parents can play a role in preventing substance abuse and peer opinion leadership programs. 1 photograph and 1 table.