Schools are expected to provide a safe environment and to play an active role in socializing children for participation in a civil society. Most schools have programs to prevent problem behavior and serious misconduct such as drug use and violence. But how good are these programs? A recent national study surveyed principals, teachers, program implementers, and students about school safety and the programs used to prevent problem behavior and promote a safe and orderly environment. Nearly all U.S. public schools are using a variety of delinquency prevention programs and disciplinary practices. Some programs and practices may be of poor quality. Problem behavior was found to be pervasive, and most common in urban schools and among children at the middle school level. Although many programs were judged potentially effective, nearly half failed to meet the study's criteria for quality. Staff training, program monitoring, and other organizational support from school leaders were found to be related to program quality. A school's organizational capacity--staff morale and stability and a history of implementing programs--predicted the extent of program use and student participation. These findings suggest that to improve delinquency prevention programs and promote safety, schools should focus on supervision, staff development, and overcoming organizational problems that have thwarted program implementation in the past. [This Research in Brief is based on "National Study of Delinquency Prevention in Schools," final report to the National Institute of Justice, July 2000, NCJ 194129 (ED459409).]