Project Abstract Common mental health disorders (CMDs), like depression and anxiety, and non-communicable diseases (NCDs), like diabetes and hypertension, are highly prevalent and are the leading causes of death and disability worldwide, especially in low-resource settings like our research site in Nepal. Comorbidity among CMDs and NCDs is high and the relationship between these conditions is complex and multidirectional. Several common behavioral risk factors worsen both conditions: stress, isolation, tobacco use, low physical activity, low quality diet, and poor treatment adherence. Behavioral interventions can address these common risk factors, and improve CMDs and NCDs. The World Health Organization's (WHO) two clinical protocols for CMDs and NCDs recommend three behavioral interventions: a) evidence-based stress reduction (EBSR) for stress/anxiety; b) behavioral activation (BA) for depression; and c) motivational interviewing (MI) for healthy behaviors. Despite this potential, these interventions are rarely available in low-resource settings because of two important gaps: 1) behavioral interventions have often been studied for one or two CMDs and NCDs, rather than for the real-world need of an integrated intervention to simultaneously address multiple CMDs and NCDs; and 2) these interventions have not been studied using implementation strategies that can support easy access (i.e., making care available at or near the patient's home) and sustained implementation in real-world settings. Based on our extensive history and long-term commitment to working in Nepal, we now propose a hybrid implementation-effectiveness study of BECOME (BEhavioral Community-based COmbined Intervention for MEntal Health and Noncommunicable Diseases) delivered by community health workers (CHWs) in Nepal. Our team has a long-standing history of conducting implementation research, integrating evidence- based care for CMDs and NCDs into existing health-care systems in Nepal, training CHWs to deliver behavioral interventions at or near patient's homes, and conducting costing analysis. We have an extensive history of collaborating with the Government of Nepal and have a deep understanding of social norms and cultural factors that drive sustained healthcare delivery. The proposed study has three aims to address the gaps identified above: Aim 1) assess the effectiveness of BECOME on depression, anxiety, and two NCDs via a stepped-wedge cluster randomized trial (20 geographic clusters) and participants (n=600) with at least one CMD and one NCD; Aim 2) assess implementation outcomes of BECOME using the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework at the patient, provider, and health system levels; and Aim 3) conduct a comprehensive costing analysis to provide strategic inputs to support long-term scale-up of BECOME. If successful, this study will provide evidence and a blueprint to the governments of Nepal and other low-resource settings...