The Wallace Foundation is funding a multiyear demonstration project to determine whether voluntary, district summer learning programs can stem summer learning loss for low-income students. Six districts--Boston, Cincinnati, Dallas, Duval County (Florida), Pittsburgh, and Rochester, New York--were selected for the demonstration project and committed themselves to offering such programs to large numbers of at-risk elementary students. These programs are all voluntary; offer reading, mathematics, and enrichment activities such as arts, sports, and science exploration; operate for a full day; provide transportation to students; are free of charge; and share a goal of maintaining or improving student achievement. They served students rising from third into fourth grade, and most served other grade levels as well. To gather information for evaluations of the six districts for the years 2011, 2012, and 2013, the authors interviewed district leaders and summer site leaders and teachers; surveyed teachers, parents, and students; observed program training, instruction, and logistics; engaged professors of elementary education reading and mathematics to review the curricula; gathered program cost data; and analyzed district data on attendance. Although the demonstration project is not complete, key lessons can be drawn in six broad areas: (1) planning; (2) curriculum; (3) teacher selection and training; (4) enrichment activities; (5) academic time on task, and (6) Program cost and funding. Lessons for school district administrators and state policymakers are discussed.