he evidence base for behavioral activation (BA) as a front-line treatment for depression is grounded in individual delivery. No valid previous meta-analytic reviews of BA delivered in groups have been conducted. This study therefore examined the efficacy and acceptability of group BA drawn from clinical trial evidence. Randomized controlled trials of group BA were identified using a comprehensive literature search. Depression outcomes at posttreatment/follow-up, recovery and dropout rates were extracted and analyzed using a random-effects meta-analysis. Treatment moderators were analyzed using meta-regression and subgroup analyses. Nineteen trials were quantitatively synthesized. Depression outcomes postgroup BA treatment were superior to controls (SMD 0.72, CI 0.34 to 1.10, k=13, N=461) and were equivalent to other active therapies (SMD 0.14, CI -0.18 to 0.46, k=15, N=526). Outcomes were maintained at follow-up for group BA and moderators of treatment outcome were limited. The dropout rate for group BA (14%) was no different from other active treatments for depression (17%). Further research is required to refine the conditions for optimum delivery of group BA and define robust moderators and mediators of outcome. However, BA delivered in groups produces a moderate to large effect on depressive symptoms and should be considered an appropriate front-line treatment option.