Ostensible psychiatric comorbidity can sometimes be explained by shared relations between diagnostic constructs and higher order internalizing and externalizing dimensions. However, this possibility has not been explored with regard to comorbidity between personality pathology and other clinical constructs in adolescents. In this study, personality pattern scales from the Millon Adolescent Clinical Inventory in a sample of 492 adolescent inpatients were subjected to a principal components analysis to yield oblique internalizing and externalizing dimensions. Relations between personality dimensions and well-established measures of psychopathology (depression, alcohol abuse, drug abuse) and other indicators of clinical dysfunction (self-esteem, suicidality, violence) were assessed before and after controlling for these higher-order personality dimensions. Associations between personality scales and indicators of psychopathology and clinical dysfunction were minimal with these higher order components controlled. These results suggest that internalizing and externalizing personality dimensions explain most of the associations between personality patterns and indicators of psychopathology and clinical dysfunction in adolescent patients.