During the summer of 2014, the Massachusetts Department of Elementary and Secondary Education 21st Century Community Learning Centers (ESE 21st CCLC) Summer Enhancement Grant Program funded 10 summer learning programs with a special emphasis on utilization of project-based learning approaches, outreach to diverse learners, and a blended academic and enrichment learning approach. Each of the selected sites had existing summer programs in place, and three of the sites (North Adams, Triton Regional, and Wareham school districts) had previously participated in the Summer Enhancement Grant Pilot. One of the key purposes of the Summer Enhancement Grant Program was to expand the best practices identified through the pilot phase with an emphasis on implementing high-quality, academically enriching summer learning experiences that can help to mitigate summer learning loss. Program sites were selected through a rigorous request-for-proposal process. Eight programs served elementary age youth and two programs served high school age youth. The 10 selected program sites served high proportions of low-performing students from low-income families, coalesced around a variety of curricular themes, and engaged in multiple partnerships with local community educational and cultural organizations. Program content, presented in the context of a blended academic and enrichment learning experience, generally focused on reinforcing the academic skills learned during the school year and helping prepare students to succeed in the upcoming school year. A profile of participating program sites is in Table 1. This Brief presents findings from research activities conducted by the National Institute on Out-of-School Time (NIOST) at Wellesley Centers for Women at Wellesley College. (author abstract)