An ex post factor design was used in which data were obtained from adolescents on a questionnaire administered anonymously in classroom settings. The extent to which these data identified direct and indirect effects of risk factors on harmful consequences of drug use and provided support for the risk factor model was investigated by means of path analysis. The study population consisted of white adolescents who were attending two high schools in an upper middle class community in Iowa. Data were collected on a single day in April 1993 by classroom teachers by means of the questionnaire. Of the 796 respondents, 412 were male and 384 female. They were about evenly distributed among grades 9, 10, 11, and 12. The path model for the sample clearly shows that selected risk factors do affect harmful effects from ATOD use above and beyond the consumption of drugs. The personality variables of alienation, trait anger, and interaction anxiety, as well as cognitive motivation for drinking apparently functioned as multiple pathway risk factors that contributed to harmful effects experienced from ATOD use independently. The results also provide substantial support for the risk factor model for predicting and explaining the development of adolescent ATOD use. 5 tables, 1 figures, 36 references, and appended study questionnaire