1. Forty participants who have a current Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revised (DSM-IV-TR) diagnosis of Major Depression will be recruited. These subjects will be randomized to receive one of two antidepressant medications: Fluoxetine or Venlafaxine ER for the duration of the study. Subjects will gradually be titrated onto the medications and will be seen in the clinic up to 18 times for medication checks, to monitor side effects and depressive symptoms, including suicidal ideation. In the event of suicidal ideation, subjects will be withdrawn from the study and referred for immediate treatment.