Out-of-school-time (OST) programs have long focused on children's social and emotional development as part of their mission of building a culture of connectedness and positive relationships between youth and adults. Research demonstrates that high-quality, evidence-based social and emotional learning (SEL) programs are associated with positive outcomes, including improved behavior, attitudes, and academic performance. This report provides tips and recommendations for incorporating high-quality SEL instruction and practices into OST programming for children and youth. The lessons are derived from the RAND Corporation's study over four years of more than 100 afterschool programs across six communities--Boston, Dallas, Denver, Palm Beach County, Tacoma, and Tulsa--participating in The Wallace Foundation's Partnerships for Social and Emotional Learning Initiative. The report summarizes a variety of approaches and actions that OST programs developed over four years to support children's social and emotional development, including adding SEL content and practices into their programming, training staff in SEL, engaging families, and adopting continuous improvement systems to monitor and refine these efforts. [For the previous report, "Strengthening Students' Social and Emotional Skills: Lessons from Six Case Studies of Schools and Their Out-of-School-Time Program Partners. Lessons from the Partnerships for Social and Emotional Learning Initiative. Volume 2, Part 1. Research Report. RR-A379-4," see ED623577.]