The University of Idaho Athletic Director directed each head coach of an athletic team at the university to schedule mandatory team meetings for the purpose of administering the survey instrument to team members. This yielded a sample of 258 student-athletes who represented 11 different types of athletic teams at the university, including both women's and men's sports. The second sample consisted of students in English 101 and 102, which all students must take to meet the English core graduation requirement, yielding a representative sample of mostly first-year students (n=607). Both samples were asked to estimate the percentage of male and female student-athletes and nonstudent-athletes at the university who had used marijuana or hashish in the past month. The sample members were also asked to self-report about whether they had used marijuana in the past month and in their lifetime. The prevalence of marijuana use in the nonathlete samples was found to be higher than the prevalence found in nationwide surveys of drug use on college campuses. Current marijuana use was higher in nonathletes than in athletes; however, lifetime use was equivalent for the two samples. The perceptions of the prevalence of marijuana use among both athletes and nonathletes exceeded self-reported use in both samples. Students who used marijuana had higher perceptions of the prevalence of marijuana use on campus, and those who believed that marijuana use was normative on campus were more likely to be current marijuana users themselves. These study findings have important implications for designing college drug prevention programs. 4 tables and 23 references