PROJECT SUMMARY Unhealthy diets significantly contribute to major preventable chronic diseases including type 2 diabetes, obesity, heart disease and stroke, which disproportionally impact racial/ethnic minority groups and those with lower income.1–3 Key health organizations agree that policies are needed to support healthier diets, including ultra- processed food and beverage taxes, nutrition warning labels, and marketing of healthier foods.4 Seven U.S. cities have sugar-sweetened beverage (SSB) taxes, the FDA is currently considering a national front-of-package food labeling system, and several U.S. cities have implemented or proposed healthy checkout regulations. It is now well-established that SSB taxes substantially reduce SSB sales and intake5 and research indicates that SSB nutrition warning labels can significantly reduce SSB purchases, though most of those data are from one- time online or lab exposures.6–8 Although taxes and warning labels targeting SSBs have been successful at shifting behavior, there are many other ultra-processed food products that contribute to unhealthy diets.9 What is less well-known is whether a suite of healthy food policies that are expanded to target a range of ultra- processed foods can shift dietary choices and intake in meaningful ways. To advance our understanding of policies needed to support nutrition security and health, our overall objective is to examine the degree to which a suite of healthy food policies in online food retailers can increase the purchase and intake of healthy foods and beverages while reducing the purchase and intake of unhealthy ultra-processed foods and beverages. To accomplish this objective, we propose using innovative online grocery store and restaurant platforms to randomize participants to either: 1) control (no taxes, warning labels, or healthy checkout regulations on any products); or 2) a suite of healthy food policies (ultra-processed food and beverage taxes, front-of-pack nutrition labeling, and healthy check out regulations that restrict the promotion of ultra-processed products on the checkout page). We will recruit 300 adults with lower income across Houston and San Antonio, TX, and Philadelphia, PA to shop once per week for eight weeks in both our online grocery store and restaurant. Week 1 will be a baseline (control) week without interventions, followed by five weeks of the interventions. In the last two study weeks, we will introduce unhealthy food marketing (e.g., banner ads) into the online platforms to mimic what we expect industry will do to counter public health policy efforts. Participants will be given money to spend in these online platforms and purchases will be delivered to them via a real food retail store and restaurant. Participants will complete surveys at baseline, 6-weeks, and 8-weeks and will complete two dietary recall interviews during the baseline week and during the fifth intervention week (4 recalls total). The specific aims are: to evaluate t...