The purpose of this study was to compare detection rates, service use, and outcomes of substance use disorder (SUD) in adolescents seeking mental health treatment. It reports detection rates, service use, and outcomes for adolescents with comorbid mental health and SUD to alert professionals to possible deficiencies in care. Participants of the study consisted of 256 adolescents and their parents or caregivers, recruited at intake from 2 outpatient and 5 inpatient treatment sites in Arkansas and Texas. Participants completed parallel, self-administered versions of the Adolescent Treatment Outcomes Module (ATOM) at intake and 6-month follow-up. The results suggest that a subset of adolescents seeking mental health treatment have comorbid SUD that may complicate treatment and affect clinical outcomes. The findings confirm the necessity of routine assessment for SUD in clinical populations. References