The California Personality Inventory and a version of the Adolescent Alcohol Involvement Scale (adapted for the assessment of marijuana involvement) were the primary instruments used. Analysis of variance and regression analysis were performed on the data. Results indicated a relationship between the personality characteristics of adolescents who are involved in marijuana use and misuse and adolescents who are not; there are discernible differences in the personalities of the adolescents who are involved with marijuana. The intervention and prevention implications of these results are discussed. (Author abstract)