Both currently depressed patients (greater than 14 on the Hamilton Depression Rating Scale) and those with a history of major depression who are clinically recovered will be included. Patients may be taking psychotropic medications for depression at the time of study. Sub-analyses will be done comparing steady-state glucose utilization rates as a function of mood state and medication status. Subjects should not have significant underlying illnesses known to affect insulin sensitivity, and should have a body mass index between 20 and 30 kg/m2.