The study, which was conducted in 2003, involved a sample of 163 adolescents and young adults (67 girls and 96 boys) ages 14 to 22. Subjects were recruited from the general population, leisure centers, and schools, as well as inpatient and outpatient units and adolescent secure residences. A French version of the Adolescent Drug Abuse Diagnosis instrument evaluated illegal drug and alcohol use and associated life-problem areas. Based on the interview, subjects were placed in three groups: those who never or only occasionally used any illegal drug (once a month maximum); those who had used drugs regularly in the past; and those who had used marijuana at least once a week during the last 3 months. An instrument developed to assess beliefs about drugs in general was adapted to assess beliefs related to marijuana. It included questions concerning marijuana's level of danger, use, motivations, and short-term and long-term consequences. Inter-group comparisons were conducted with the analysis of variance, using the post-hoc comparisons. Findings show that subjects' opinions differed according to their experience with marijuana use. Current regular users believed marijuana to be less dangerous, while believing that alcohol and heroin were more dangerous, when compared with the beliefs of never/occasional and past users. Current and past users were more likely to view marijuana use as a means of coping with stress compared to never/occasional users. Never/occasional users tended to attribute more negative consequences to marijuana use, such as diminished driving ability and school performance, as well as a pathway to hard drugs. 6 tables, 1 figure, and 32 references