Playworks is a program that aims to create “safe, inclusive school environments where kids can grow, lead, and thrive” (Playworks, 2013a). Through trained, full-time coaches focused on recess in low-income elementary schools across the country, Playworks provides opportunities for inclusive play and physical activity. The Robert Wood Johnson Foundation engaged Mathematica Policy Research and the Gardner Center to conduct a rigorous evaluation of Playworks. Twenty-nine schools interested in implementing Playworks were randomly assigned to treatment and control groups during the 2010–2011 (cohort 1) or 2011–2012 (cohort 2) school year. During the one-year study period for each cohort, treatment schools received Playworks and control schools were not eligible to implement Playworks. Data collection took place at 25 cohort 1 schools in spring 2011 and an additional 4 cohort 2 schools in spring 2012 to document the implementation of Playworks and assess the program’s impact on key outcomes related to play, physical activity and recess. Additional analyses document the implementation of Playworks and its impact on school climate, academic learning, students’ social skills and behavior.