SUMMARY – PROJECT 1 Nationally, 73.6% of adults are overweight or obese. Rural populations and persons living in low-income households have high rates of obesity. The greatest disparities in obesity prevalence between urban and rural counties are in the southern United States. Arkansas has the sixth highest proportion of rural population (~41%) and the third highest obesity prevalence (37.4%). The CDC estimates 18.5% of children age 2-19 in the US are obese. Arkansas has the third highest rate of obesity for high school students (22.1%) and the fifth highest rate for children in ages 10-17 (20.2%). Obesity contributes to increased diabetes incidence, cancer incidence and mortality, and cardiovascular disease incidence and mortality among rural communities. This application seeks funding to evaluate a Comprehensive School Nutrition Enrichment Intervention (CSNEI) for the first time in rural schools. The primary research question is: “Compared with demographically similar school districts that did not implement the CSNEI, does the CSNEI policy intervention yield improved obesity prevention outcomes among rural K-12 students?” We will conduct a matched-pairs cluster randomized trial with pre-test and repeated post- tests in 6 school districts, 3 implementing CSNEI and 3 matched comparison school districts. The evaluation will include ~11,500 students in 6 school districts: ~5,750 from CSNEP school districts and ~5,750 from matched comparison school districts. The study will explore heterogeneity of treatment effects for race/ethnicity, sex, age, and economic status to understand effects on populations most at risk for obesity. Our specific aims are: Aim 1.A Evaluate the effects of a CSNEI on students' relative (accounting for age and sex) BMI change over time. Aim 1.B Evaluate the short-term and long-term effects of a CSNEI on the nutritional quality of food served in school meals. Aim 1.C Evaluate the short-term and long-term effects of a CSNEI on students' consumption of food served in school meals. Aim 1.D Evaluate the short-term and long-term effects of a CSNEI on students' skin carotenoid levels, as an indicator of fruit and vegetable intake. Aim 2 Conduct an implementation study to document barriers and facilitators of CSNEI implementation in rural schools. We will complete the first implementation study of a CSNEI in rural schools, which will provide critical information to ensure successful implementation of similar interventions in school districts and will be an innovative step to accelerate translation of evidence into broad practice. Existing paradigms for the study of comprehensive school nutrition interventions do not appropriately address needs and potential barriers of rural children, particularly those living in low-income households. This study will fill critical gaps in evidence by rigorously evaluating a CSNEI in rural schools with high proportions of students eligible for free and reduced price meals (>50%); employing a matched-pairs cluster randomized design to compare changes in BMI z-scores over time; and incorporating economic status, age (in months), sex, and race/ethnicity in the analyses.