For a group to be considered a gang it must have a name or identifiable leader, claim a territory or criminal enterprise, have regular association among members, and engage in delinquent or criminal behavior. Psychological factors that increase the risk of youngsters joining gangs include the need for affiliation, the need for achievement but without prospects, lack of responsibility for self and influence of others, learned helplessness, low self-esteem, lack of positive role models, and boredom. Social factors that increase the risk of gang affiliation include family history of gang involvement, low socioeconomic status, community norm, limited world view, cultural barriers and prejudices, lack of employment possibilities and education, media glorification of gangs, and desire for safety and protection. The article also discusses family dynamics and parenting problems that increase the risk of gang affiliation, ways parents can help prevent youngsters' association with gangs, and community and national intervention strategies. Figures, glossary, references, bibliography