Social and emotional learning (SEL) is the process by which children and adults learn to understand and manage emotions, maintain positive relationships, and make responsible decisions. This is the second in a series of four related reports about what is known about SEL programs for students ages 3-8. The report series addresses four issues raised by the Regional Educational Laboratory (REL) Mid-Atlantic's Early Childhood Education Research Alliance: characteristics of effective SEL programs (part 1), implementation strategies and state and district policies that support SEL programming (part 2), teacher and classroom strategies that contribute to social and emotional learning (part 3), and outcomes of social and emotional learning in different student populations and settings (part 4). This report offers guidance on program implementation and identifies trends in integrating this learning at the state, district, and school levels. Resources on state and district supports for implementing social and emotional learning are appended. [For part 1, "A Review of the Literature on Social and Emotional Learning for Students Ages 3-8: Characteristics of Effective Social and Emotional Learning Programs (Part 1 of 4). REL 2017-245," see ED572721. For part 3, "A Review of the Literature on Social and Emotional Learning for Students Ages 3-8: Teacher and Classroom Strategies that Contribute to Social and Emotional Learning (Part 3 of 4). REL 2017-247," see ED572723. For part 4, "A Review of the Literature on Social and Emotional Learning for Students Ages 3-8: Outcomes for Different Student Populations and Settings (Part 4 of 4). REL 2017-248," see ED572724.]