This bulletin addresses questions about the interrelatedness of youth gangs, drugs, and violent crime, discussing whether drug trafficking is a main cause of violence in youth gangs or only a correlate, and noting whether there are other important sources of gang violence. Section 1 presents a historical overview of gang drug use and trafficking, noting the growing involvement of youth gang members in drugs and violent crime. Section 2 examines the current image of youth gangs, discussing the differences between street gangs and drug gangs and examining the connection between youth gangs and adult criminal organizations. Section 3 looks at studies of the relationship between youth gangs, drugs, and violence. This section reviews other important sources of violence in the gang context, focusing on two sources: youth gang homicide and drug trafficking (including the role of firearms in gang violence) and the causes and correlates of youth gang violence. Long-term studies of adolescent samples are examined. After summarizing research findings, the bulletin presents policy and program implications, focusing on ways to break the cycle. (Contains 145 references.) (SM)