Major late life depression (LLD) is an important health problem with a large and growing number of affected individuals. A significant subset of patients with LLD, particularly those with vascular depression, have abnormalities in certain parts of the brain that are evident on MRI scans and may be associated with poor acute and long-term response to antidepressant treatment. Studies have also indicated that LLD patients frequently have frontal lobe dysfunction. A longitudinal study with the antidepressant nortriptyline has demonstrated that frontal lobe dysfunction is associated with poor acute response and a greater risk for recurrence of LLD. However, it is not known if this finding applies to other antidepressants. This study will be the first clinical trial to simultaneously test the effects of specific brain and psychological factors on course of response, remission rate, and other measures of health outcomes in people with LLD.