Toward this end, the validity of the conduct disorder hypothesis of adolescent drug abuse, primarily tested to date on normal youth samples, was examined in a drug clinic-referred sample (n = 2,582). All subjects met DSM-III-R criteria for either abuse of or dependence on at least one psychoactive substance. Based on self-report data, it was hypothesized that a delinquency factor would account for the most variance in drug use compared to three competing factors (psychological distress, nonconventional values, and family distress). Support for the hypothesis was obtained across gender, age, and ethnic groups. The delinquency factor uniquely accounted for approximately 50-60 percent of the variance in drug use severity. Confirmatory prediction analysis of individual scales showed that peer chemical environment and deviant behavior (both part of the delinquency factor) and, to a lesser degree, psychological disturbance (part of the psychological distress factor), were consistently the most predictive of drug use. These findings are consistent with the view that delinquency behaviors are important mediators of adolescent drug abuse and, thus, they merit central attention in prevention programs. 19 references