Access to parks and green spaces can improve health and well-being by promoting physical activity, reducing stress, and improving mental health. Millions of Americans lack access to parks within a ½ mile of their home. A study proposes to use a community-engagement process to study the impact of increasing access to a park using the Tacoma Green Schoolyards initiative in Washington state. The initiative aims to promote public access to school properties and renovate schoolyards in neighborhoods without access to parks within a 10-minute walk. The study will use a pre-post longitudinal study design with a comparison site, using both quantitative and qualitative methods. Outcomes of interest will be identified through community engagement and may include measures related to physical and mental health, academic performance, social and community factors, participatory design effectiveness, and environmental attitudes. Results can inform policies and programs for decision makers in school districts, parks planning and management, and healthcare providers and researchers.