In the United States, an estimated 55 million students are enrolled in pre-kindergarten through twelfth grade. Another 15 million students attend colleges and universities across the country. While U.S. schools remain relatively safe, any amount of violence is unacceptable. Parents, teachers, and administrators expect schools to be safe havens of learning. Acts of violence can disrupt the learning process and have a negative effect on students, the school itself, and the broader community. School violence is a subset of youth violence, a broader public health problem. Youth violence refers to harmful behaviors that may start early and continue into young adulthood. It includes bullying, slapping, punching, weapon use, and rape. Victims can suffer serious injury, significant social and emotional damage, or even death. The young person can be a victim, an offender, or a witness to the violence, or a combination of these. This fact sheet addresses questions about (1) the extent of violence in the United States; (2) short- and long-term effects; (3) risk factors for perpetuating youth violence; (4) prevention efforts; and (5) CDC's four-step approach to address public health problems like school violence. The guide also contains a list of resources.