This document draws on more than 50 years of gang program evaluations to summarize what has been learned about: (1) prevention programs, including early childhood, school-based, and afterschool initiatives; (2) intervention programs, including those that work to create violence-free zones, establish gang summits and truces, and rehabilitate gang members; (3) suppression programs, including those focused on prosecution, police response, geomapping, and other tracking systems; (4) strategies using multiple techniques, such as community policing; (5) multiagency initiatives; (6) comprehensive approaches to gang problems; and (7) federal, state, and local legislation. The summary also describes a nationwide assessment of youth gang prevention, intervention, and suppression programs sponsored by the Office of Juvenile Justice and Delinquency Prevention. The summary debunks stereotypes surrounding youth gang members and provides research-based recommendations for enhancing the effectiveness of youth gang programs and strategies. A directory of programs, strategies, and organizations, and an index are attached. (Contains 5 tables, 5 figures, and 243 references.) (SLD)