Empirical data indicate American Indian youth are vulnerable to ill health due to adverse socio-demographic indices and little physical activity, sedentary behaviors and inadequate nutrition. These factors, which form a toxic triangle of risk, are compounded by behavioral risks factors such as alcohol, tobacco, and other drug use (ATOD). If current patterns persist, by 2050 one out of three youth from the Choctaw Nation of Oklahoma, the third largest AI tribe, will be living with Type 2 diabetes and 70% of the Nation will be obese. Wakaya: Rising Up for Choctaw Youth Health, is an experiential, outdoor, nature-based program grounded in Choctaw values. It is a multi-level intervention that integrates components of motivational interviewing, the information- motivation-behavioral skills model, the Positive Youth Leadership Development framework, and the NIMHD Multilevel Socio-Ecological Research Framework. With a prospective two-group randomized waitlist-control trial design among 176 at-risk Choctaw youth (ages 14-18 years), we will assess the culturally grounded intervention's impact on the primary outcomes of physical activity, sedentary behavior, and healthful food habits; as well as the secondary outcomes of weight/BMI; and ATOD. Additionally, guided by the NIMHD Multilevel Socioecological Framework, we will examine the potential mechanisms of change by analyzing how pathway variables (e.g., nature connectedness) mediate intervention effects. Finally, through Topic Modeling of qualitative interview data and Ripple Effect Mapping via youth participant and tribal leader focus groups (n=64), we will explore the community-level impact of Wakaya and create a visual map representing the interconnected ripple effects of the intervention into the community. The program, supported by promising preliminary data on this approach among adults and acceptability data from youth, involves a 3-month outdoor intervention (with 4 individual sessions, weekly group sessions, 2 overnight culture immersion camps (7 days total), and a 4-day Choctaw Trail of Tears walk. Additionally, the intervention builds youth health leadership and community organizing skills. The research team comprises experts in American Indian health from academe as well as Choctaw Nation and collaborative efforts among two tribal Departments- Historic Preservation and Behavioral Health. Findings will be disseminated scientifically as well as shared with the tribe for programmatic implementation. If efficacious, this intervention will provide evidence for interventions that promote physical activity and nutrition programs that target green spaces, community gardens, natural/nature trails, and built environments. The proposed study provides significant and practical information in several areas, including the feasibility of delivering interventions in nature-based settings across multilevel stakeholders. Should it be efficacious, the program has potential for widespread adaptation and dissemina...