In 2019, the Texas legislature passed a historic education finance bill that included an initiative to add up to 30 days to the school-year calendar. One way districts can do this is to offer a voluntary summer learning program. In 2020, the American Institutes for Research, with support from The Wallace Foundation, launched the six-year Texas Summer Learning Study in collaboration with the state education agency and its partners. This brief highlights findings from the first 4 years of the 6-year study. The goal is to elevate lessons learned about how state policies and supports--such as those in Texas--can facilitate local education agencies' (LEAs') design and implementation of evidence-based summer learning programs and also to describe what the implementation of those evidence-based programs looks like at the local level. Researchers conducted interviews with and administered surveys to staff at more than 60 local education agencies, interviewed the Texas Education Agency and its partners, analyzed program administrative data, reviewed planning tools and resources, and observed programming in a sample of districts. With the support of a competitive grant program, districts developed comprehensive strategic plans for their summer programs that incorporated 10 research-based design principles. Early findings suggest that districts adopt these principles more frequently, consistently, or with greater fidelity to the evidence when they are required or strongly encouraged by the state.