This article investigates the utility of the quadrant classification of co-occurring substance use and depressed mood in adolescents. The addition of developmentally risky but diagnostically subthreshold symptoms was hypothesized to improve the utility of co-occurring disorder classification. Methods: Data from the 2008 National Survey of Drug Use and Health were utilized. Adolescents were classified by severity of depression and substance abuse symptoms into single and co-occurring disorder groups. Results: Lowering the depression and substance use thresholds for categorizing adolescents as having co-occurring disorders maintained the utility of the quadrant model co-occurring disorders classification system and marginally improved the prediction of service utilization. Conclusions: The quadrant model of classification is appropriate for adolescents. The inclusion of developmental risk factors in addition to diagnostic indicators is useful in predicting a broad population of adolescents who use services.