Increasingly, the definition of gang refers to juveniles and young adults in all 50 States who associate for serious, especially violent, criminal behavior. While the scope and seriousness of the gang problem are unclear, there is evidence for an increase in gang-related violence and increasing involvement in drug trafficking. Generally, gangs are loosely organized and consist of core, regular, peripheral and recruit members. Variables of class, culture, race, or ethnicity of gangs interact with local community factors of poverty, social instability, and/or social isolation to account for the variety of problems that exist. Gang membership provides certain psychological, social, cultural, and economic functions not adequately fulfilled by the family, school, or legal employment. Four basic strategies have evolved in dealing with youth gangs: community organization or neighborhood mobilization, youth outreach, provision of social and economic opportunities, and gang suppression and incarceration. Social agency youth development and law enforcement suppression strategies have predominated, and often clashed with each other.