The participants attended nine high schools chosen to obtain a dispersed study group to represent the geographic and socioeconomic distribution of the province's population. Five of the focus groups involved Hispanic youths and were conducted in Spanish; the other 44 groups were conducted in English. Participants attending two of the schools were ethnically diverse and included many first-generation immigrants from Portugal and several different Asian countries. About one-third of the students attending one of the two northern schools consisted of aboriginal Canadians. Each focus group lasted about 1.5 hours and was tape recorded. Results revealed four basic assumptions. First, students believe that marijuana has little or no effect on demeanor; thus, its use by itself is unlikely to attract the attention of the police. Second, students regard the most probable outcome of an encounter with the police as confiscation of the marijuana and not arrest. Third, students believe that many police officers use marijuana. Fourth, students believe that ethnicity and social class are crucial variables in determining both the likelihood and the outcome of an encounter with the police. Findings suggested that the police and young middle-class marijuana users regard marijuana in similar terms and that, under the circumstances, it makes little sense to have police officers deliver messages at variance with what they are presumed to believe and do. Notes and 26 references (Author abstract modified)