The purpose of this study was to explore the relationships among summer reading camp participants' initial prosocial efficacy, reading motivation, and their reading skill changes. Despite the theoretical explanation of social and emotional learning (SEL), there is a lack of empirical studies demonstrating the complex relationships and processes among students' social-emotional competencies and beneficial academic learning outcomes. The Freedom Schools reading camp provides learning opportunities during the summer vacation for children primarily from low-income families and minoritized racial and ethnic backgrounds. This study tested the linear relationship between students' initial reading motivation and reading growth with prosocial efficacy as a moderator (n = 67). We found that initial intrinsic regulation was related to students' reading comprehension skill growth, and prosocial efficacy moderated the relationship between reading skill changes and intrinsic regulation. Results provided clues about how students' efficacy for prosocial behavior could explain the relationship between students' reading motivation and reading growth.