Examines the validity of the conduct disorder hypothesis of adolescent drug involvement on a large drug clinic-referred sample (N=2,582). It was hypothesized that factors of delinquency would account for the most variance in drug use compared to three competing factors (psychological distress, nonconventional values, and family distress). Analyses provide support for the hypothesis across gender, age, and ethnic groups. (Contains 31 references.) (Author/GCP)