Adolescents are disproportionately represented as both victims and perpetrators of fatal and nonfatal assaultive violence. Homicide rates among young men in the United States are vastly greater than those of other Western industrialized nations. Persons ages 12-24 years face the highest risk of nonfatal violent victimization of any segment of American society. Arrest rates for homicide, rape, robbery, and aggravated assault peak among adolescents and young adults. Arrest rates for murder and other violent crimes increased substantially among the age group since the mid-1980s. The article's three main objectives are: (1) to describe the demographic variation and trends in homicide, violent crime (assault, robbery, and rape), and physical fighting among adolescents and young adults; (2) to examine the impact of interpersonal violence in the school setting; and (3) to discuss individual and broader societal factors that contribute to violence, and their implications for preventing violence among youth. Notes, tables, figures, references