The report defines youth gangs, noting characteristics including structure, membership, ethnicity, location, identity, criminal activities, initiation, and leadership. The extent of the problem is discussed in terms of the incidence of juvenile gangs, incidence of gang violence, and characteristics of gang violence. The patterns of gang violence in Los Angeles are briefly described. Some characteristics of juvenile gangs are examined in more detail; organization and structure; incentives; participation; activities; development; and prison gang influence. There are several ways to identify juvenile gangs through their graffiti, hand signals, tattoos, colored bandanas, headgear, and slang. Prominent theories on juvenile gangs are summarized. The law enforcement response to juvenile gangs has been characterized by three common organizational approaches: youth service programs; gang details; and gang units. Youth gang control by police departments encompasses intelligence, enforcement, investigation, apprehension, and even prevention. The report concludes with description of several successful youth gang programs including, inter alia, Operation Safe Streets in Los Angeles, CRASH sponsored by the Los Angeles Police Department, and Crisis Intervention Network in Philadelphia.