The discussion of gang origins, composition, and characteristics addresses early formation and research; contemporary status and types of gangs; graffiti and hand signals; girls in gangs; and revenues and expenditures. An overview of responses to gangs outlines components of community strategies. They may involve fundamental changes in the way that schools operate; job skills development for youths and young adults, accompanied by improvements in the labor market; assistance to families; changes in the way the criminal justice system responds generally to problems, specifically gang problems; and intervention and control of known gang members. A typology of gang prevention encompasses suppression, social intervention, organizational change, community mobilization, and social opportunities. Related suppression and intervention techniques are reviewed. Case studies from Boston, MA, and San Mateo, CA, illustrate how community-oriented policing and problem solving can counter gangs. 52 references