A review of the extent of the problem of youth violence notes that in 2000, an estimated 199,000 youth homicides (9.2 per 100,000 population) occurred globally; and between 1985 and 1994, youth homicide rates increased in many parts of the world, especially among youth between the ages of 10 and 24. Studies of nonfatal violence show that for every youth homicide there are approximately 20-40 victims of nonfatal youth violence who receive hospital treatment. In discussing risk factors for youth violence, the chapter advises that participating in physical fights, bullying, and carrying weapons are significant risk behaviors for youth violence. In addressing the dynamics of youth violence, the chapter discusses how youth violence begins and situational factors that increase the incidence of youth violence. A review of the risk factors for youth violence considers individual factors (biological, psychological, and behavioral); relationship factors (family influences and peer influences); community factors (gangs, guns, drugs, and social integration); and societal factors (demographic and social changes, income inequality, political structures, and cultural influences). In discussing what can be done to prevent youth violence, the chapter describes individual approaches, that encompass the development of protective factors associated with individual skills, attitudes, and beliefs; relationship approaches, which can include home visitation, training in parenting, mentoring programs, and therapeutic approaches; community-based efforts, which can involve community policing, curtailing the availability of alcohol to youth, extracurricular activities, and the suppression of gang violence; and societal approaches, which counter poverty and gun violence among youth. Recommendations focus on the establishment of data collection systems, more scientific research, the development of prevention strategies, and the dissemination of knowledge. "Boxes" within the chapter briefly discuss a profile of youth gangs and the impact of media on youth violence. 4 tables and 186 references