Background: The US obesity prevalence has increased from 30.5% in 1999 to 41.9% in 2020, and the medical cost of obesity is estimated at $173 billion annually. Given the health and cost implications of obesity and its direct relationship with the growing prevalence of diabetes, there is a need to identify policy levers that can ameliorate these public health burdens. Complete Streets policies aim to strengthen transportation systems, promote physical activity and improve health outcomes related to obesity and in turn diabetes. It addresses issues like sidewalks, bicycle lanes, bus lanes, public transportation stops, crossing opportunities, median islands, accessible pedestrian signals, curb extensions, modified vehicle travel lanes, streetscape, and landscape treatments. This study examines the effect of state adoption of Complete Streets policies on prevalence of obesity. Methods: We combined data on state obesity rates from America's Health Ranking database with legal information on state's adoption of Complete Streets policies from the PHACCS Initiative. Using the data we estimated overall average, as well as state specific, policy effects due to Complete Streets policy adoption. Our approach utilized a generalized difference-in-difference design and additional testing of model assumptions. Results: Our analysis sample consisted of a panel of 1,479 state-year observations (across 50 US States and the District of Columbia, for the period of 1990-2018). This corresponds to 22 exposed states (with Complete Streets policies), and 29 control states (without Complete Streets policies). Preliminary analyses indicate significant reduction of obesity prevalence (-0.5%; 95%CI: -0.9 to -0.1; p=0.006) in exposed vs. control states, with heterogenous policy effects across states. Conclusions: Complete Streets policy adoption is associated with reduced obesity rates. Given these associations, Complete Street policy adoption is also likely to result in reductions in prevalence of diabetes. Disclosure S.Linde: None. L.E.Egede: None. Funding National Institute of Diabetes and Digestive and Kidney Disease (K24DK093699, R01DK118038, R01DK120861 to L.E.E.); National Institute for Minority Health and Health Disparities (R01MD013826 to L.E.E.)