The Playworks program, an initiative of the Robert Wood Johnson Foundation, places full-time coaches in low-income schools to provide opportunities for organized play during recess and throughout the school day. Using random assignment, Mathematica and the John W. Gardner Center for Youth and Their Communities (JGC) at Stanford University are conducting the first rigorous evaluation of the implementation and impact of the program across 25 schools. Findings based on the first cohort of schools included several significant, positive impacts. Playworks had a positive impact on teachers' perceptions of students' safety and feeling more included during recess. Teachers in Playworks schools also reported less bullying and exclusionary behavior during recess, and found transitions from recess to classroom learning were less difficult than teachers in control schools found. Teachers in Playworks schools reported significantly better student behavior at recess and readiness for class than teachers in control schools and were also more likely to report that their students enjoyed adult-organized recess activities. Students in Playworks schools reported better behavior and attention in class after sports, games, and play than students in control schools. Overall, most teachers, students, and principals reported positive perceptions of the Playworks program.