This article describes mindfulness-based cognitive therapy (MBCT). Developed as a therapy to address the prevalence of major depression relapse, it offers an 8-week group-based programme which combines mindfulness-based stress reduction with components of cognitive behavioural therapy (CBT), and is increasingly being offered by social workers worldwide. MBCT is based on an interacting cognitive subsystems model (ICS) replacing Beck's schema model. While this model represents the largest shift in the approach to major depression for social work in two decades, social work has been slow to incorporate it into its research agenda. In practice, MBCT teaches patients who are in remission from depression to become aware of, and relate differently to, their thoughts, feelings, and bodily sensations – a shift from CBT's schema theory that focused primarily on the content of thoughts and beliefs. A few reviews of MBCT research exist, but there has been no review of the mechanics of MBCT and how it addresses the cognitive patterns or meta-cognition and processes of major depression, and there is no review of its use within the social work literature. This paper outlines the mechanisms of MBCT in relation to the components of depression relapse/reoccurrence and reviews the literature regarding the effectiveness of MBCT. The paper concludes that MBCT has the potential to positively contribute to interventions directed at relapse prevention for patients with a history of depression.