In an attempt to compare different methods for assessing personality disorder, this study compared the Millon Clinical Multiaxial Inventory-II (MCMI-II; Millon, 1987), a self-report questionnaire, and the Personality Disorder Examination (PDE; Loranger, 1988), a semistructured clinical interview. Subjects (N = 97) were mental health outpatients of a health maintenance organization in New England. The instruments were compared in terms of the presence of personality disorder, the number of diagnoses assigned to a patient, and agreement in specific diagnoses and in cluster assignment. Agreement between the two instruments was low; the two instruments exhibited greater agreement in predicting the absence of diagnoses than their presence. Agreement was best for the borderline and avoidant diagnoses. Correlations between scales exhibited somewhat better agreement than was evident for diagnoses. Analyses at the cluster level resulted in moderate correlations between the instruments. Very high intracluster correlations were found for the MCMI-II, but not for the PDE.