The cohort of the current study consists of more than 45,000 Swedish conscripts, and the association between cannabis consumption and the development of schizophrenia over a 15-year follow-up was examined. The study, based on data from the 1969–1970 survey of conscripts, included information on drug habits, social background, and psychiatric history. The cohort, primarily consisting of men born in 1951, was tracked through Sweden's national register of psychiatric care until 1983.