More Outside Your Door (MOYD) - ABSTRACT The Rural Alaska Community Action Program (RurAL CAP), which administers Head Start schools in rural Alaska, reports that 68% of Alaska Native children ages 3 to 5 years are overweight and 43% are obese. Diet, physical activity, and sleep hygiene are primary risk factors for childhood obesity, a risk factor for cardiometabolic diseases later in life. Notably, subclinical cardiovascular pathology can be detected as early as 3 years of age. Once living off the land and sea, Alaska Native (AN) people have suffered decades of colonization and in-migration, which have interfered with traditional food consumption, signaling a striking change in local food systems. Diet and physical activity are prime targets for early intervention, as taste preferences and exercise habits established in childhood forge lifelong adherence. Thus, we have designed More Outside Your Door (MOYD), a multilevel intervention, which at the individual level builds on our prior efforts to promote traditional diet and activities to decrease risk for obesity in AN preschoolers. At the family level, MOYD provides feedback to parents about their child’s health screenings; at the school level, it features traditional foods, outdoor traditional physical activities, and a culturally centered curriculum. At the community level, it offers resources to improve the built environment for safe outdoor play that invites all community members to participate. In partnership, the Alaska Native Tribal Health Consortium, RurAL CAP, and collaborators will refine and test the effectiveness of MOYD at 12 Head Start preschools in the Yukon-Kuskokwim region: (1) we will use qualitative methods with Head Start staff, parents, and community Elders to optimally tailor MOYD for southwest Alaska communities; and (2) we will conduct a stepped-wedge group-randomized trial to test its effect on children’s diet, physical activity (PA), body mass index (BMI), and other risk factors for obesity-related chronic disease over three years. Primary outcomes are diet (classroom meals, actigraphy-based physical activity, and body mass index. Secondary outcomes include individual child level measures of hemoglobin levels and educational and developmental progress; parent report of diet, activity, and sleep at home; and measures of traditional foods/sugar-sweetened/processed foods by carbon and nitrogen stable isotope ratios using fingernail clippings. We will also measure outcomes at the school level (classroom meals, outdoor time) and community level (objective data on use of play space). (3) We will conduct a process evaluation using the RE-AIM framework. Our Specific Aims are to (1) conduct preschool staff and parent/elder workgroups to refine the MOYD intervention for optimal effectiveness for obesity prevention among AN preschool children; (2) test the effectiveness of MOYD on a) diet, PA, outdoor time, and BMI; and b) improving other clinical and behavioral risk factors for obesity-related chronic disease in preschool children; and (3) implement the RE-AIM framework to evaluate dissemination and implementation of the MOYD intervention in Head Start programs.