A new RAND Corporation study shows that voluntary summer programs can benefit children from low-income families, particularly those with high attendance. Programs studied in five school districts had several elements in common: a mix of academics and enrichment activities, certified teachers, small class sizes, full-day programming provided five days a week for five to six weeks, at least three hours of instruction in math and English language arts daily, no fee for participation, and free transportation and meals. High attenders outperformed control group students on tests in both math and English language arts after the second summer of participation. RAND offers practical recommendations to districts as they implement summer learning programs.