Mindfulness-based cognitive therapy (MBCT) is a recently developed class-based program designed to prevent relapse or recurrence of major depression (Z. V. Segal, J. M. G. Williams, & J. Teasdale, 2002). Although research in this area is in its infancy, MBCT is generally discussed as a promising therapy in terms of clinical effectiveness. The aim of this review was to outline the evidence that contributes to this current viewpoint and to evaluate the strengths and weaknesses of this evidence to inform future research. By systematically searching 6 electronic databases and the reference lists of retrieved articles, the authors identified 4 relevant studies: 2 randomized clinical trials, 1 study based on a subset of 1 of these trials, and 1 nonrandomized trial. The authors evaluated these trials and discussed methodological issues in the context of future research. The current evidence from the randomized trials suggests that, for patients with 3 or more previous depressive episodes, MBCT has an additive benefit to usual care. However, because of the nature of the control groups, these findings cannot be attributed to MBCT-specific effects. Further research is necessary to clarify whether MBCT does have any specific effects.