This study tested the hypothesis that dually diagnosed adolescent substance abusers could be matched to effective treatments on the basis of their comorbid psychopathology. Specifically, patients with externalizing disorders would have better outcomes when treated with cognitive-behavioral group treatment (CBT), and subjects with internalizing disorders without comorbid externalizing disorders would fare better in interactional group treatment (IT). Thirty-two dually diagnosed adolescent substance abusers were randomized into two 12-week manual guided outpatient group psychotherapies: CBT and IT. At 3-month follow-up, no patient-treatment matching effects were identified. Adolescents assigned to CBT demonstrated a significant reduction in severity of substance use compared with those assigned to IT. Improvement in severity of family function showed a trend in favor of CBT. School function, peer-social relationships, legal problems, and psychiatric severity all showed a consistent nonsignificant direction in favor of CBT over IT. CBT appears to be a promising short-term psychosocial intervention for adolescents.