ABSTRACT
This study examined the relationship between treatment processes and posttreatment abstinence using data from the Drug Abuse Treatment Outcomes Studies for Adolescents (N = 810), with a focus on differences between adolescents with and without a comorbid mental disorder. The majority of the sample (62%) was diagnosed with at least one co-occurring mental disorder, most often conduct disorder. Overall, comorbid youth had more service needs and received more services compared with non-comorbid youth, and there were significant differences in service delivery by type of treatment modality. Posttreatment abstinence among the comorbid youth was positively associated with rapport with counselors and participation in 12-step groups while in treatment.