The National Summer Learning Project, launched by the Wallace Foundation in 2011, is a six-year study offering the first assessment of the effectiveness of voluntary, district-led summer learning programs offered at no cost to low-income, urban elementary students. The study, conducted by RAND, uses a randomized controlled trial and other analytic methods to assess the effect of district-led programs on academic achievement, social-emotional competencies, and behavior over the near and long term. All students in the study were in the third grade as of spring 2013 and enrolled in a public school in one of five urban districts Boston; Dallas; Duval County, Florida; Pittsburgh; or Rochester, New York. The study follows these students from third to seventh grade. The primary focus is on academic outcomes but students' social-emotional outcomes are also examined, as well as behavior and attendance during the school year. Among the key findings are that students with high attendance in one summer benefited in mathematics and that these benefits persisted through the following spring; students with high attendance in the second summer benefited in mathematics and language arts and in terms of social-emotion, outcomes; and that high levels of academic time on task led to benefits that persisted in both mathematics and language arts. Book jacket.