PROJECT SUMMARY Despite the benefits of physical activity (PA) to prevent cardiovascular disease (CVD) and other chronic diseases, few adult Latinas meet PA guidelines. Given the central role of faith-based organizations (FBOs) within the Latino community and their commitment to the well-being of their members, FBOs are ideal settings for health promotion. Evidence-based approaches for increasing PA and reducing obesity such as Faith in Action exist, but few PA interventions go to scale. Implementation strategies that enhance the capacity of FBO leaders and community health workers (promotoras) to implement EBIs can facilitate their uptake. We propose to enhance Faith in Action with three organization-level strategies designed to increase program fit and effectiveness: 1) training FBO leaders in health promotion 2) tailoring messaging to enhance fit between Faith in Action and each unique FBO context, and 3) empowering promotoras to advocate for organizational change. Given the need to improve strategies to sustain health programs in community settings, we propose to test the influence of two additional sustainment strategies: 1) strengthening community collaborations and 2) providing technical support. We will conduct a hybrid type II effectiveness-implementation trial using a clustered RCT design to test the impact of the proposed implementation strategies on organization-level change and individual behavior in diverse FBOs for a 12-month intervention and 6-month follow-up. Thirty-two FBOs will be randomly assigned to a Standard EBI condition (Faith in Action as originally implemented), an Enhanced condition (Standard condition + organizational-level implementation strategies), or Enhanced + Sustainment condition (Enhanced implementation condition + sustainment strategies). We will collect quantitative and qualitative data at baseline, 6 months, 12 months, and 18 months post baseline. The proposed study aims to: 1) Test the short and long-term impacts of organization-level implementation strategies in 2 Enhanced conditions on organizational outcomes compared to the Standard EBI condition, 2) Examine individual reach and effectiveness among Latinas (n=812) in FBOs in the 2 Enhanced conditions compared to the Standard EBI condition. Secondary aims examine theoretical mechanisms of action (e.g., organizational climate) and the additional impact of two sustainment strategies. Informed by the Practical Robust Implementation and Sustainability Model (PRISM) and Reach Effectiveness-Adoption Implementation and Maintenance (RE-AIM) frameworks, the current study will use mixed methods to adapt Faith in Action to diverse FBOs. This research is innovative because it experimentally tests organization-level implementation strategies and their associated mechanism of action in Latino FBOs' from diverse denominations. Our findings will impact the field by providing rigorously derived evidence for the scale-up of innovative EBIs in FBOs. If successful, findings...