The tripartite model of anxiety and depression has received strong support among child and adolescent populations. Clinical samples of children and adolescents in these studies, however, have usually been referred for treatment of anxiety and depression. This study investigated the fit of the tripartite model with a complicated sample of residential youths with externalizing problems. Structural Equation Modeling was used to test the tripartite model relationships between negative affect, positive affect, and mood symptoms. Multiple fit indices were used to provide a reliable and conservative evaluation of the model. As predicted, the tripartite model provided a good fit for symptoms of emotional disorders in this complicated sample of children and adolescents. Implications of these findings are discussed in terms of the utility of the tripartite model in understanding anxiety and depression in more diverse populations and recommendations for residential assessment.