In order to test the hypothesis that adolescent substance abusers could be matched to effective treatments on the basis of their comorbid psychopathology, 32 dually diagnosed adolescents were randomized into two short-term outpatient group psychotherapies: cognitive-behavioral treatment (CBT), and interactional treatment (IT). Two follow-up assessments were conducted at 3 and 15 months after planned treatment completion. As reported recently, at the three-month follow-up, no patient-treatment matching effects were identified. However, adolescents assigned to CBT demonstrated a significant reduction in severity of substance abuse compared to those assigned to IT. At 15-month follow-up, there were no differential improvements as a function of therapy type. However, subjects in general maintained significant treatment gains on the substance abuse, family function, and psychiatric status domains of the Teen-Addiction Severity Index (T-ASI), and both CBT and IT were associated with similar long-term gains. Large scale, randomized, controlled treatment studies are further recommended to examine the findings of this small-scale pilot study.