There is a striking disparity between the number of individuals with significant mental health concerns and those who are able to access care globally. One promising solution to expanding the mental health taskforce is task-sharing, or employing nonspecialists in the delivery of evidence-based interventions. Behavioral activation (BA), a brief intervention that focuses on scheduling rewarding activities into one’s daily life, may have promise for delivery using task-sharing approaches due to its straightforward, flexible nature. The aim of this systematic review was to examine the current state of the literature on non-specialist-delivered BA and evaluate the evidence base of this approach. Three databases (Pubmed, PsycInfo, and Cochrane) were searched, and all articles were screened for inclusion criteria by two research assistants, included the review of titles, abstracts, and full-text. The final dataset consisted of 13 research studies, represented through 15 articles. A meta-analysis was conducted to examine the overall pooled effects of peer-delivered BA on depressive symptoms (the most widely examined clinical outcome). Studies reported on effectiveness and implementation outcomes of non-specialist-delivered BA for depression, substance use, loneliness, trauma survivors, and individuals with comorbid physical health conditions. Results provide initial support for the effectiveness of BA utilizing a task-sharing approach, and highlight the feasibility and acceptability of using nonspecialists to deliver BA in a variety of contexts, including low-resource settings.Copyright © 2023. Published by Elsevier Ltd.