To compare the short-term and long-term efficacy of two different treatment approaches in widespread use in clinical settings for treating patients with post-traumatic stress disorder (PTSD): fluoxetine (which acts directly on biological systems) vs a psychological treatment, Eye Movement Desensitization and Reprocessing (EMDR). To clarify: 1) the differential treatment effects of these different treatment modalities; 2) whether symptom improvement is accompanied by changes in pathophysiology; and 3) the long-term effectiveness of these treatments.