Youth violence occurs when persons aged 10-24 years, as victims, offenders, or witnesses, are involved in the intentional use of physical force or power to threaten or harm others. Youth violence typically involves young persons hurting other young persons and can take different forms. Examples include fights, bullying, threats with weapons, and gang-related violence. Different forms of youth violence can also vary in the harm that results and can include physical harm, such as injuries or death, as well as psychological harm. Youth violence is a significant public health problem with serious and lasting effects on the physical, mental, and social health of youth. In 2013, 4,481 youths aged 10-24 years (6.9 per 100,000) were homicide victims. Homicide is the third leading cause of death among persons aged 10-24 years (after unintentional injuries and suicide) and is responsible for more deaths in this age group than the next seven leading causes of death combined. Males and racial/ethnic minorities experience the greatest burden of youth violence. Rates of homicide deaths are approximately six times higher among males aged 10-24 years (11.7 per 100,000) than among females (2.0). Rates among non-Hispanic black youths (27.6 per 100,000) and Hispanic youths (6.3) are 13 and three times higher, respectively, than among non-Hispanic white youths (2.1). The number of young persons who are physically harmed by violence is more than 100 times higher than the number killed. In 2013, an estimated 547,260 youths aged 10-24 years (847 per 100,000) were treated in U.S. emergency departments for nonfatal physical assault-related injuries.