Personality disorders (PDs) are long-standing, maladaptive patterns of thinking, feeling, and behaving associated with impairment in functioning and/or subjective distress. The goal of this study is to demonstrate that the DSM PDs are reliably diagnosed, and distinguishable in terms of demographic factors, psychosocial variables such as recent life events and social support, and childhood history of trauma and abuse. There are uncertainties and disagreements about how best to asses the PDs. In this project we will examine the comparability of PD assessments made by different methods, and the influence of diagnostic methodology on diagnostic reliability, and validity. Specifically, we will examine the effect of acute psychiatric state on PD evaluations, compare patients and close informants as information sources, and compare questionnaire and interview measures. During the 4 years of patient intake we will evaluate 600 nonmanic, nonpsychotic, nonorganic psychiatric inpatients age 18-45. The first 50 patients will participate in a joint-interview, one-day test-retest reliability study. The remaining subjects will receive a more extensive evaluation including PD assessments at admission and discharge, and a baseline psychosocial and axis I evaluation. For all subjects, the patient and a close informant will be independently interviewed. We will test the hypothesis that the 13 DSM PDs are distinguishable by the overall pattern of their associations with demographic variables, axis I diagnoses, and preadmission psychosocial history. We will also examine five questions regarding the comparability of the DSM-III, DSM-III-R, and (draft version) DSM-IV criteria. 1) What is the degree of overlap and diagnostic concordance between the systems? 2) Have successive DSM editions reduced the comorbidity amongst the PDs? 3) Have the convergent and discriminant validity of the individual criteria improved in the more recently developed criteria? 4) Are the interrater and short-interval test-retest reliabilities comparable in the three criteria sets? 5) Do the correlates of PDs vary across systems?