Interest in social emotional learning (SEL) is higher than ever, as parents, educators, and policymakers recognize that children need more than cognitive skills for later life success. However, most SEL research has been conducted in formal education settings. This article describes results from an empirical study of 4-5 years old SEL in two informal learning settings, including children's museums and community playgrounds. Members of the Children's Museum Research Network observed 606 preschool children using the Revised/Shortened Minnesota Preschool Affect Checklist (MPAC-R/S). Findings show that preschool children engaged in SEL in both settings, but that significantly more instances of SEL were seen in children's museums compared with community playgrounds. We argue that children's museums may provide an important, peer-to-peer opportunity for children to develop and practice their SEL, one that is unique from the more common teacher-child interactions provided in schools.