The increasing frequency and intensity of extreme weather events, such as heat waves, is disproportionately impacting the health of racial/ethnic minority and low-income populations. There is an urgent need to develop climate-smart solutions for heat stress in marginalized communities, addressing both direct effects on health (e.g., death, heat stress) and indirect impacts on food and water supplies. To meet this need, the Center for Climate: Equitable and Accessible Research-based Testing for Health (C-EARTH) will use a community- centered approach to combat heat stress, recognizing that locally tailored, culturally appropriate climate-smart solutions are essential for sustainability. Our research project will assess the impact of heat stress on vulnerable populations in three distinct settings at established partner locations. Each site addresses the escalating heat-related health impacts of climate change on a different scale: Boston focuses on individuals, Madagascar focuses on small communities in rural, remote zones, and South Africa focuses on households in urban built environments. At each project site, we will analyze associations between heat exposure and heat stress and other heat-related health outcomes, utilizing a standardized questionnaire across all sites. Then, in close partnership with community organizations at each site, we will implement and test cooling solutions that promote resilience to heat stress for the most vulnerable members of these communities through intervention studies and cohort-controlled research. For the intervention studies, we will address the following aims: 1) determine whether educational resources and a cooling solution in 100 subjects improves health and thermal condition outcomes for high-risk older adults with chronic disease and material hardships in Boston; 2) evaluate the feasibility, use, and health impact of cooling centers with HEPA filters and freezers for fish storage in four communities in Madagascar; and 3) determine whether a passive housing cooling solution improves indoor temperatures and health outcomes in a subset of 32 households in South Africa. Together with our core teams, we will implement these solutions with community partners, evaluate their effectiveness, and develop methods to translate our findings towards policy. The breadth of cultural systems, ecological zones, and economic vulnerability of our three sites will ensure a diversity of settings for generalizing and scaling successful interventions. If successful, we will be able to scale this approach from individuals to national levels, enhancing climate resilience and health equity.