Key points: What can K-12 schools do to help support social and emotional learning (SEL)? One rarely discussed idea is to analyze the world of early childhood education. In the best early childhood programs, SEL is an integral part of the teaching strategy and an area in which performance is carefully measured. At the same time, more research is needed on early childhood's SEL implementation and impacts. Early childhood's use of SEL holds out five main takeaways for K-12 leaders. (author abstract)