The underlying conditions where youth live are associated with population health outcomes, with rural communities facing under-studied challenges. Youth physical activity (PA), a key risk factor linked to later cancer occurrence, is an outcome of community conditions. The proposed work will address a critical public health need by evaluating the impact of a whole-of-community multi-level adaptive systems intervention on implementation of community change and youth population PA. Our intervention, Wellscapes, is based on a hierarchical patch dynamics paradigm, given that communities are ?wellness landscapes? of spatially heterogeneous geographic areas, characterized by a patchwork of interacting organization and activity settings. The intervention will establish a multi-level system infrastructure (Community Hub, Organization Wellness Teams, Activity Setting/Leaders) and provide training and support for population health quality improvement cycle processes targeting two evidence-based practices (EBPs): (1) stacking time segments of PA episodes within an organization?s daily routine, and (2) improving the quality of PA episodes (% time in PA). Our omnibus hypothesis is that intervention communities (plus organizations and leaders nested within) will have synergy and capacity to implement EBPs, adapting to continuously changing local system drivers to create a whole-of-community ecosystem of diverse and equitable youth PA opportunities. Building on local health department partnerships, we will conduct a two-wave staggered-start community randomized trial with four volunteer rural communities (each having nested school, after-school, scouting/4-H club, youth sport organizations) randomly assigned to intervention or standard public health practice. For baseline and intervention years, one day per month in the fall (3 days) and spring (3 days), organization activity settings (e.g., classrooms, teams) that house 480 children in 3rd through 6th grades will be assessed, resulting in observed community condition data, PA accelerometer data, and setting reach data (children % attendance by gender, ethnicity, free/reduced lunch status, and grade). We will also obtain estimates of population level PA with the use of the calibrated Youth Activity Profile, as well as community system qualitative data. The specific aims are to: (1) Determine the impact of the intervention on multi-level community system outcomes; and (2) Determine the implementation system drivers of multi-level youth population PA. We will use ?big data? multi- level modeling methods for this effectiveness-implementation hybrid design, because there is a dual focus on testing an implementation strategy while simultaneously evaluating youth population PA impact. The research is significant because it evaluates a method for improving population health, theory-based systems, and behavior change processes in low-resource rural communities. The proposed research is novel because the adaptive patch dynamics approach builds capacity for both equitable collaboration and EBPs implementation across multiple local systems that are individually and collectively, dynamic and unpredictable. !