This article examines the relationship between psychiatric disorder and the use of tobacco, alcohol, marijuana and hard drugs during adolescence. The sample of 1,302 adolescents aged 12 to 16 came from households selected by stratified, cluster and random sampling of the 1981 Canada Census. Symptom checklists were used to approximate diagnoses of conduct disorder, attention deficit disorder and emotional disorder. Logistic regression analyses indicated that conduct disorder was strongly related to all types of substance use and that emotional disorder was related to the use of tobacco, alcohol and hard drugs. These relationships were true for the adolescents' self-assessments only; the parents' assessments of psychiatric disorder were not related to the adolescents' reports of substance use.