Social and emotional learning (SEL) is a fundamental part of education. Incorporating high-quality SEL programming into day-to-day classroom and school practices has emerged as a main goal for many practitioners over the past decade. The present article overviews the current state of SEL research and practice, with a particular focus on the United States. The need for a model of SEL that goes beyond the classroom is illustrated, and a systemic approach to implementing SEL school-wide is introduced. It is argued that school-wide SEL maximises the benefits of SEL programming by becoming the organising framework for fostering students' potential as scholars, community members, and citizens. Further, a Theory of Action (ToA) developed by the Collaborative for Academic, Social, and Emotional Learning (CASEL) is presented that serves as a blueprint for implementing systemic SEL in schools. Potential challenges and barriers involved in moving toward school-wide SEL implementation are considered and discussed.