This application requests 5 years of funding for the Clinical Research Center (MHCRC) for the Study of Suicidal Behavior. There are approximately 33,000 suicides per year in the United States and ten times that number of suicide attempts. to respond to this major health problem, we must improve on current predictors of suicide risk which have high sensitivity but inadequate specificity. Recently identified reductions in serotonin function in serious suicide attempters and the brain of suicide victims create hope that more specific predictors of suicide risk may be found. Studies of treatment interventions to reduce suicide risk require specific predictors in order to identify a high risk group. A multidisciplinary approach is necessary to develop a predictive model for suicidal behavior because potential risk factors are demographic, social, developmental, psychiatric, genetic and biological. Cross-sectional identification of risk factors and ultimately prospective testing requires high risk populations where the frequency of suicidal behavior is sufficient to test risk factors. This suicide research approach requires a CRC structure to permit an integrated approach to a multidimensional problem. the MHCRC emphasizes an integrated biobehavioral approach. The initial phase has involved establishment of a working MHCRC structure and cross-sectional assessment of potential risk factors. successful study of 140 patients in the first 18 months, a significant growth in related RO1-supported research, development and testing of research instrumentation, and training of investigators and staff are indices of significant progress. Four methodological advances distinguish the clinical studies of suicide attempters and nonattempters. First, an integrated series of multi-disciplinary measures (social, demographic, psychological, psychiatric and biological) evaluate hypothesized risk factors for suicidal behavior and allow estimation of the relative separate and common variance explained by these indices. Second, measures made in different adult patient populations including affective disorders and schizophrenia and in adolescents will establish which risk factors are disease-specific. Third, a prospective follow-up study has been initiated in MDE and schizophrenic patients to test promising predictors suggested by cross-sectional study. Fourth, results of these clinical studies together with results of the extensive program of concurrent psychological and biological study of completed suicides will be employed to generate an integrated model of suicidal behavior.