Subjects will be enrolled and first treated openly for 14 weeks with escitalopram; 58 escitalopram responders will then be randomized to double-blind continuation treatment with escitalopram or placebo for 6 additional months. Our primary aim is to compare time to relapse and relapse rates in responders to acute escitalopram who are then randomized to placebo versus continuation treatment with escitalopram. Secondary/exploratory aims will explore 1) Whether subjects who receive continuation escitalopram perform better on secondary outcome measures (e.g., quality of life) than those on placebo; 2) Change in symptoms with continuation of escitalopram during the continuation phase; and 3) Acute treatment response.