Although suicide and suicide attempts have long been known to be associated with "depression", most studies of this association have suffered from methodologic flaws, e.g., retrospective diagnostic assessments, unreliable diagnostic categories, mixed diagnostic samples or the equally serious drawback of having focused on one or other domain of potential predictor variables. The present study will employ structured clinical interviews for diagnosis according to the DSM-III-R criteria. A cohort of 200 hospitalized patients with Major Depressive Episodes (135 attempters, 65 non-attempters) will receive extensive diagnostic, behavioral and biological assessments. These patients will be studied in a cross- sectional manner as part of the NIMH-funded Clinical Research Center for the Study of Suicidal Behavior at the University of Pittsburgh. This study now seeks to conduct a prospective study of outcome in this unique cohort of patients with regard to suicidal behavior. Patients will be reassessed for clinical state, life events and suicidal behavior 3 months, 12 months and 24 months after discharge. This will be the first such comprehensive psychobiological, prospective study of predictors of suicidal behavior. Since, determinants of suicidal behavior are derived from multiple domains including psychopathologic, genetic, biologic, psychologic, familial and psychosocial, the development of a general explanatory or predictive model of suicidal behavior or completed suicide is dependent on the simultaneous assessment of potential risk factors from multiple domains in the same patient population. The testing of such a predictive model for suicidal behavior requires a prospective follow-up study such as the one proposed here. The major hypotheses of the present study are that the presence of a major depressive disorder, clinical behavior dimensions (e.g., hopelessness, substance abuse), life events and biological measures (CSF 5- HIAA, prolactin response to fenfluramine, platelet 5-HT2 receptors) will hypotheses is that the depressive episode, behavioral dimensions, biological indices, and treatment intensity will vary in terms of being state or trait-dependent and short or long-term predictors and that predictors of high medical damage and planned suicide attempts will differ from predictors of impulsive, low medical damage attempts. Exploratory studies will involve testing predictors of suicide completers and a comparison will be made of predictors of high and low planning, medical damage suicide reattempts versus completion.