Neuropsychological dysfunction in major depression appears to contribute to the risk for suicidal behavior. We have recently demonstrated that depressed past attempters making severe suicide attempts can be discriminated from less severe attempters, non-attempters, and controls on the basis of deficits in executive functioning, that are independent of deficits typically found in depressed patients regardless of past suicide history. The purpose of this study is to clarify the nature of these executive function deficits in past attempters, in order to identify those measures that will be most effective for identifying suicidal risk. We will contrast the performance of depressed past suicide attempters (n=50) and depressed non- attempters (n=50) on measures of executive functioning (abstraction, working memory, fluency, and impulsiveness) and on measures sensitive to cognitive performance impairments typically found in depression (general intellectual performance, attention, verbal memory, and visual memory). We hypothesize that past suicide attempters will perform more poorly than non-attempters on executive functioning measures, but no worse on depression- related measures. All subjects will be washed out of psychotropic medication for baseline evaluation. These samples will be followed for one year, and assessed again to determine the effect of treatment on the persistence of these deficits. A sample of non-patients (n=50) will be assessed with the same battery at both time points in order to establish performance standards for comparisons of attempters and non-attempters. The specific aims of this project are to determine if (1) past attempters are uniquely impaired on executive function measures during an acute episode of depression, and if (2) their unique deficits remit after treatment or persist. Data from this study will provide much-needed information about a neglected realm of functioning in those at risk for suicide and identify the impairments in thinking that might be used to predict suicidal behavior.