Parental reports of adolescent substance use were compared to the adolescents' self-reports using identical scales. Congruence was defined as exact agreement on whether adolescents were current users, ex-users, or never-users. Both parents were found to be less accurate in predicting their adolescents' alcohol use compared to cigarette or marijuana use. Single mothers were significantly less likely to be congruent than were mothers from two-parent households. Mother and father congruence on all substances was unrelated to the adolescent's sex, race, or after school employment. For both parents, congruence for adolescent marijuana use was significantly related to the age and GPA of the adolescent. Congruence may also reflect important properties of family functioning, as significant relations were found between both adolescent and parent ratings of family cohesion and parent-adolescent congruence on perceptions of marijuana use.