This revised, competing continuation Stage II study proposal is in response to NIDA's Behavioral Therapies Development Program (PA-99-107). A randomized clinical trial is proposed to evaluate the direct, mediated, and moderated effects of Integrated Family and Cognitive-Behavioral Therapy (IFCBT), a multisystems treatment for adolescent drug abuse with promising efficacy results. In the first study aim, we seek to evaluate the separate and possibly synergistic effects of family systems and cognitive-behavioral IFCBT components on posttreatment drug abuse problem severity, problem behavior, psychiatric distress, and academic achievement of adolescent drug abusers. Innovative analytic strategies are subsequently used to evaluate the degree to which successful outcomes are attributable to specific familial and cognitive-behavioral change processes targeted by IFCBT components. The possibility of effect-modification also is considered, with a focus on neurocognitive, psychiatric comorbidity, and demographic factors. Namely, we seek to understand how variations in specific client characteristics, such as executive dysfunctions or psychiatric comorbidity, might explain why treatments work for some drug abusing youths but not others. In addition to promising findings on IFCBT efficacy, this Stage II proposal benefits from the development and Stage I study application of (a) treatment manuals; (b) therapist training procedures; (c) therapist adherence and competence tools; (d) a neuropsychological battery to assess cognitive functions; (e) a psychodiagnostic battery to assess comorbid psychiatric disorders; and (f) a study assessment battery comprised of therapeutic process and outcome measures. This revised application has sought to address well-taken concerns cited by the reviewers while maintaining proposal strengths. The lack of adolescent drug treatment research continues to be a serious gap in the addictions literature despite alarmingly high rates of drug abuse among youth and the range of morbidities and mortality that result nationwide. If successful, this project should help to identify specific behavior change processes targeted by family systems and cognitive-behavioral treatments that foster subsequent reductions in drug use and problem behavior among recovering youth. Neurocognitive and psychiatric influences on adolescent drug treatment outcomes appear to be significant yet are poorly understood. Increasing our understanding of relationships between client characteristics, skill development during treatments, and subsequent outcomes should also help to improve adolescent drug treatments.