This research proposal is intended to elucidate the efficacy and mechanisms underlying Mindfulness Based Cognitive Therapy (MBCT) in a population in remission from recurrent Major Depressive Disorder (MDD). The first objective of the study is to replicate previous studies' findings of MBCT's effects on decreasing depressive symptoms and depression relapse rates. However, this proposal aims to make a novel contribution to the literature by using a randomized, controlled design, and comparing the effects of MBCT to an active control condition (ACC). The use of a well-designed ACC will enable us to control for confounding variables such as social support and expected outcomes, thus allowing us to determine whether elements specific to MBCT lead to its salutary effects (Aim 1). Previous MBCT studies have largely relied on self-report measurement methodologies, limiting valid conclusions about the nature of MBCT. Further, few studies have examined the mechanisms underlying effects of MBCT on depressive symptoms and relapse. Theoretical considerations and preliminary empirical evidence suggest emotional, physiological, and cognitive functioning to be promising mechanisms of MBCT. Therefore, the investigators propose to assess each of these potential mechanisms of MBCT using self-report, autonomic physiological, and reaction time tasks (Aim 2). Collectively, these aims are expected to strengthen the evidence base for MBCT while cultivating a scientific model for its effects and mechanisms on decreasing depressive symptoms and depression relapse rates.

Inclusion Criteria:

• must comprehend English well
• be 18-55 years of age
• meet enhanced DSM-IV criteria for remission of MDD, recurrent and have a history of three or more previous episodes of DSM-IV major depression in the absence of a history of mania or hypomania
• at least one of those episodes was within the past two years
• participant must be in remission and if on antidepressant medication (ADM), they must be on a stable dose with no change in type or amount for past 12 weeks or participants must be off ADM at T1 for at least the preceding 12 weeks
• have, at screening assessment, residual depressive symptoms indicated by a Beck Depression Inventory-II (BDI-II;[72]) score between 6-19.

Exclusion Criteria:

• bipolar disorder
• schizophrenia or borderline personality disorder
• current suicidal thoughts and/or suicide attempt in last two months
• current anxiety disorder if it constitutes the predominant aspect of the clinical presentation and requires primary treatment not offered in the project
• substance abuse or dependence within last three months
• dementia or subnormal intellectual potential
• current obsessive-compulsive disorder
• current eating disorder
• history of previous mindfulness training or more than eight lifetime sessions of CBT
• current use of psychotherapy or counseling