Marie Denise Singh was a 43-year-old married librarian who presented to an outpatient mental health clinic with a history of recurrent bouts of depression. Most recently, she described feeling depressed during the month since she began a new job. She said she was preoccupied with concerns that her new boss and colleagues thought her work was inadequate and slow and that she was unfriendly. She had no energy and enthusiasm at home, either, and instead of playing with her children or talking to her husband, she tended to watch television for hours, overeat, and sleep excessively. This had led to a 6-pound weight gain in just 3 weeks, which made her feel even worse about herself. She had begun to cry several times a week, which she reported as the sign that she "knew the depression had returned." She had also begun to think often of death but had never attempted suicide. Ms. Singh said her memory about her history of depressions was a little fuzzy, so she brought in her husband, who had known her since college. They agreed that she had first become depressed in her teens and that she had experienced at least five separate and distinct periods of depression as an