The paper is divided into three parts. Part I reviews the causes of gang formation. Part II reports the negative impact that gang activities have on a community, and Part III addresses viable community prevention strategies and explains why current gang policies fail. To address gangs and gang activities, communities are forming alliances that draw on the resources of parents, schools, police, religious institutions, community organizations, businesses, and youth. Community policing is an important resource for countering gangs. Communities form partnerships with law enforcement agencies in an effort to reduce gang criminality. Community residents create neighborhood watch programs for self-protection, and another mechanism involves clean-up programs to rid neighborhoods of graffiti. Schools are also an important resource for preventing gangs. Constructive educational programs can help prevent dropping out of school, and other school-related programs include removing graffiti, banning gang attire and symbols, creating and enforcing school safety policies, and forming gang-resistance curricula. Handgun violence is a serious problem associated with gangs. The criminal justice system and communities must find ways to reduce the accessibility and volume of handguns in neighborhoods. A comprehensive family policy is needed to address the underlying causes of gangs. Such a policy might include the following components: universal health care; subsidized high-quality child care; nutritional services for poor children; universal preschool for children who are educationally at risk; after-school programs for the children of working parents; and schools that provide educational, social, and recreational activities. Public policy has been ineffective in countering gang activities for four reasons: a lack of comprehensive gang policies in inner-city areas, failure to alleviate poverty conditions, failure to tailor policies to the causes of gangs, and failure to conduct effective evaluations of gang-prevention programs. 38 references