This article presents an evaluation of the first 2 years of a research-based summer learning program that provided self-selected and developmentally appropriate books to students in low-income and low-resource elementary schools by a local philanthropic organization in a large urban district. The evaluation found evidence of a positive effect of participation in the program on the state year-end standardized reading assessment but found no statistically significant effects on the proximal measures of reading achievement in the fall after summer vacation. The article also provides an analysis of implementation of the program and lessons learned that could be useful to other organizations that are interested in implementing similar programs.