Worldwide some 250,000 homicides occur among youth 10–29 years of age each year, which is 41% of the total number of homicides globally each year ("Global Burden of Disease", World Health Organization, 2008). For each young person killed, 20-40 more sustain injuries requiring hospital treatment. Youth violence has a serious, often lifelong, impact on a person's psychological and social functioning. Youth violence greatly increases the costs of health, welfare and criminal justice services; reduces productivity; decreases the value of property; and generally undermines the fabric of society.