DESCRIPTION (provided by applicant): It has been estimated that each new episode of depression increases a patient's cumulative risk for relapse by 16% and those patients who have experienced three or more past depressions are at an elevated risk of staying chronically depressed (Solomon 2000). Patients with recurrent depression are, therefore, a logical group for targeted prevention efforts. To date, the best validated and most widely used approach for preventing relapse in recurrent depression is maintenance medication. However, the protection afforded lasts only as long as patients continue to take their medication. In light of this concern, there has been a growing interest in the use of treatments that combine recovery through medication with psychological prevention of relapse/recurrence (Fava et al., 1998). One such treatment is Mindfulness-Based Cognitive Therapy (MBCT), a group intervention designed to train recovered depressed patients to disengage from mood-linked depressive thinking styles that may trigger relapse/recurrence. While there are preliminary data on MBCT's preventative effects, we do not know how well this treatment fares in comparison with the most pervasive preventive intervention for depression, namely maintenance medication. We plan to identify a sample of 272 recurrently depressed outpatients and, during the acute treatment phase of this study, provide antidepressant medication. Remitted patients will then be randomly assigned to receive either maintenance medication, be withdrawn from medication and receive MBCT or be withdrawn and receive placebo and clinical management. All patients will then be followed for the next eighteen months. Our main hypotheses are that MBCT and maintenance medication will not differ in their efficacy, and that both will outperform placebo and clinical management. We will also perform analyses to examine a possible cognitive mechanism underlying MBCT's effectiveness as well as estimate the relative costs of MBCT compared to maintenance medication for prevention of relapse. Findings from this study would have clear public health significance because MBCT could prove to be an additional effective treatment for recurrently depressed patients who require maintenance courses of treatment to prevent relapse/recurrence.