The notion of educating the "whole child" generally includes at least the abilities to (1) develop healthy personal relationships; (2) treat others with respect and dignity; (3) develop the cognitive capacity to solve problems and think creatively; (4) succeed in postsecondary education and the labor market; and (5) be a contributing citizen in a democracy. To nurture these capacities, schools should be healthy, caring spaces that create a climate of support for equitable pathways for children to reach these goals while also creating a challenging and dynamic learning environment. Social and emotional learning (SEL) is critical for the development of these capacities. In 2017, the National Commission on Social, Emotional, and Academic Development convened a 28-member Council of Distinguished Scientists to examine the relevant evidence regarding SEL across a range of disciplines. The council concluded that social and emotional competencies are essential to learning; positive development; and success in school, careers, and life. Its report cited research over the past two decades that has demonstrated the impact of SEL on a variety of child outcomes, including children's well-being, behavior, and academic outcomes. High-quality SEL programming also has been found to have a positive impact on teachers and other staff and leads to improvements in school culture and climate. This report reviews the findings from 12 independent meta-analyses covering hundreds of studies of school-based SEL programs, presents the evidence on the effects of social and emotional learning programs in PreK-12 schools, and considers the next steps for research in SEL. [This study was supported by the Whole Child Policy Table, an LPI project funded by the Carnegie Corporation of New York, Chan Zuckerberg Initiative, William and Flora Hewlett Foundation, Harmony and Inspire at National University, Pure Edge, Inc., and the Wallace Foundation. For the research brief, see ED630375.]