Universal school-based social and emotional learning (SEL) interventions seek to improve the social-emotional competencies (e.g., self-awareness, self-management, social awareness, relationship skills, responsible decision-making) of students through explicit instruction in the context of learning environments that are safe, caring, well-managed and participatory. In recent years, SEL has become a dominant orthodoxy in school systems around the world. In this important new book, leading researchers provide a comprehensive overview of the field, including conceptual models of SEL; the assessment of social and emotional competence in children and young people; key issues in the implementation of SEL interventions; the evidence base on the efficacy of SEL in improving students' outcomes; and critical perspectives on the emergence of SEL. It will be essential reading for anyone interested in the role of schools in promoting children's wellbeing. This book was originally published as a special issue of the Cambridge Journal of Education.