This appendix augments a report that updates our 2013 guidance to school district leaders and their partners across the country who are interested in launching summer learning programs or improving established ones. In that report, we present recommendations based on our evaluations, conducted between 2011 and 2016, of summer programs in five urban school districts. The Wallace Foundation selected these districts--Boston; Dallas; Duval County, Florida; Pittsburgh; and Rochester, New York--for the National Summer Learning Project (NSLP), a multiyear assessment of the effectiveness of voluntary, district-led summer learning programs offered at no cost to low-income, urban, elementary students. The five districts are among the nation's most advanced in their experience with comprehensive, voluntary summer learning programs. (author abstract)