A growing body of evidence indicates that the test scores of low-income children drop significantly relative to their higher-income counterparts during the summer months. This study used random assignment to evaluate the effectiveness of the Building Educated Leaders for Life (BELL) program--a summer program designed to improve academic skills, parental involvement, academic self-perceptions, and social behaviors among low-income children and families--and finds that a well-implemented summer learning program can improve reading test scores and increase the extent to which parents encourage their children to read during the subsequent school year. These findings provide some support for investments in out-of-school time programming for low-income children during the summer, such as those currently coming from the 21st Century Community Learning Centers program and the Supplemental Services provisions of Title I of the No Child Left Behind Act.