The Survey of School-Based Gang Prevention and Intervention Programs is a study of approaches used by schools to reduce or prevent gang involvement among schools. Principals in a probability sample of 1,287 schools were asked what they were doing in their schools to prevent problem behavior or to promote a safe and orderly school environment. Responses of 848 principals reported a surprisingly large number of prevention and intervention activities, which were used as a basis for sampling programs for more detailed scrutiny. In a second phase, information was requested for 14 categories of intervention activity from more than 550 schools. Responses represented more than 16,000 students in 310 schools and more than 13,100 teachers in 404 schools. Data suggest that schools are engaging in a great deal of activity to reduce problem behavior generally and to prevent or reduce gang involvement in particular. However, much of that activity is weak and would not be expected to have much of an effect because it fails to use practices known to be effective, is limited in intensity, or is extended to only a few individuals. The quality of school efforts could probably be improved through better training and supervision of intervention activities. Contains 14 tables. (SLD)