The students included 203 low-risk typical high-school students and 160 youths at high risk of school problems and dropout. They completed an extensive three-part questionnaire. Drug involvement was conceptualized as drug use frequency, drug access, drug use control, and adverse consequences of drug use. Results revealed that high-risk youth, compared to low-risk youth and national statistics, endorsed a much greater breadth and depth of drug use, greater access to drugs, less control of drug use, and greater adverse consequences due to use. A secondary analysis showed that low-risk experimenters were similar to high-risk youth in their access to drugs and their eroding drug use control, but showed low frequencies of drug use and negligible adverse use consequences. Findings also indicated that measuring and exploring these four aspects of drug involvement provided a clear description of the adolescents' drug milieu and revealed differences in patterns of drug involvement that would not have been clear by looking solely at drug use frequency. Figures, tables, footnotes, and 24 references (Author abstract modified)