Presence of personality disorders was assessed with the Structured Interview for the DSM-III Personality Disorders (SIDP) in a series of 78 nonpsychotic inpatients with major depression. Measures of severity of depression were administered at admission, at discharge, and 6 months after admission. Outcome for the depression was especially poor in patients meeting criteria for multiple personality disorders from multiple DSM-III clusters. A subgroup of 38 patients received both the SIDP interview and a self-report measure of personality disorder, the Personality Diagnostic Questionnaire. Depressed inpatients who met more than the median number of personality disorder criteria by either measure were approximately half as likely to show improvement at discharge and at 6-month follow-up than were patients with less than the median number of criteria.