ImportanceThe global refugee crisis disproportionately affects the Muslim world. Forced displacement often results in trauma-related mental health issues. Effective psychotherapy exists, but there are barriers to uptake by refugee groups as well as a lack of culturally appropriate interventions.ObjectiveTo examine the efficacy of a brief, lay-led, mosque-based intervention, Islamic Trauma Healing (ITH), adapting empirically supported cognitive behavioral principles to improve mental health and well-being.Design, Setting, and ParticipantsIn a randomized clinical trial, 101 participants received ITH or active assessment but delayed intervention (waiting list [WL]) in mosques and virtually in Seattle, Washington, and Columbus, Ohio, and were assessed through 12-week follow-up. Data were collected from July 14, 2018, through July 14, 2022, and data analysis was conducted from March 13 to July 31, 2023. United States–based refugees from Somalia who experienced a Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) Criterion A trauma exposure and posttraumatic stress disorder (PTSD) reexperiencing or avoidance. Analyses were intention-to-treat, using full information likelihood for missing data.InterventionIslamic Trauma Healing included psychoeducation, discussion of the lives of prophets who had undergone trauma, and informal prayer turning to Allah about the trauma, incorporating cognitive restructuring and imaginal exposure. Lay-leader training is purposely brief: two 4-hour sessions with weekly supervision.Main Outcomes and MeasuresThe primary outcome was PTSD severity (measured with the Posttraumatic Diagnostic Scale for DSM-5 [PDS-5]). Secondary outcomes included depression (Patient Health Questionnaire-9), somatic symptoms (Somatic Symptoms Severity-8), and quality of well-being (World Health Organization Five Well-Being Index). Analyses were intention-to-treat.ResultsAnalyses were based on all 101 randomized participants (92 [91.1%] women; 9 [8.9%] men; mean [SD] age, 46.5 [12.02] years) with baseline mean (SD) PDS-5 score of 31.62 (16.55) points. There were significant differences in PTSD severity (d = −0.67), depression (d = −0.66), and well-being (d = 0.71), comparing ITH vs WL after the intervention. Gains were maintained through 12-week follow-up. Islamic Trauma Healing was consistent with religious and cultural practices (mean [SD], 3.8 [0.43]) and promoted community reconciliation (mean [SD], 3.8 [0.42]).Conclusions and RelevanceIn this randomized clinical trial of a brief, lay-led mental health intervention, ITH proved superior to WL. The findings suggest that ITH has the potential to provide an easily trainable and scalable intervention, incorporating Islam and empirically supported principles, that addresses the psychological wounds of war and refugee trauma.Trial RegistrationClinicalTrials.gov Identifier: NCT03502278