The students completed personal interviews and a questionnaire that included several psychological scales and test batteries. The analysis focused on 125 psychosocial variables and used an index of severity of drug use to clarify the role of various causal factors at different levels of drug abuse. Results appeared to confirm the suggestions in the research literature that drug use has become a normal, predictable form of behavior that accompanies adolescent development. In addition, low-self-esteem does not appear to be related to drug use, and psychopathological factors are important in severe drug abuse. Findings indicated the need for programs that recognize the roles of the family and social environments and for research focusing on the prediction of severe drug abuse. Tables and 18 references (Author abstract modified)