This research summary explores READS and the rigorous research behind its development over the years, as well as the program's outcomes and key components. The brainchild of James Kim, a Harvard University education professor, READS provides 10 free, carefully-matched books to third through fifth graders over the summer, along with three key supports: a reading comprehension routine taught to the students at school before their summer vacation begins; the engagement of the students' families in the program; and keep-up-the-reading nudges from teachers through texts or other communications during the summer. Over the course of more than a decade, Kim developed READS and refined its design based on what he and colleagues were learning from a series of randomized controlled trials examining various versions of the program. The largest of these studies, involving more than 6,000 second and third graders in 59 moderate- and high-poverty schools, found that READS participants made average gains equivalent to nearly one month of reading skills. For students in the highest poverty schools, the average gains were nearly 1.5 months.