This study examined the presence of personality disorders in adolescent inpatients with major depression (MDD; n = 45), substance use disorders (SUD; n = 27), or both disorders combined (MDD-SUD; n = 42). A consecutive series of patients were given structured diagnostic interviews for Axes I and II disorders. The groups did not differ with regard to age, gender, ethnicity, socioeconomic status, psychiatric history, or global assessment of functioning. Borderline personality disorder was diagnosed more frequently in the MDD-SUD group than in the MDD or the SUD groups.