Children are exposed to violence every day in their homes, schools, and communities. They may be struck by a boyfriend, bullied by a classmate, or abused by an adult. They may witness an assault on a parent or a shooting on the street. Such exposure can cause significant physical, mental, and emotional harm with long-term effects that can last well into adulthood. In 1999, OJJDP created the Safe Start Initiative to prevent and reduce the impact of children’s exposure to violence through enhanced practice, research, evaluation, training and technical assistance, resources, and outreach. The initiative has improved the delivery of developmentally appropriate services for children exposed to violence and their families. Understanding the nature and extent of children’s exposure to violence is essential to combating its effects. Partnering with the Centers for Disease Control and Prevention, OJJDP has sponsored the most comprehensive effort to date to measure children’s exposure to violence. The National Survey of Children’s Exposure to Violence is the first survey to ask children and caregivers about exposure to a range of violent incidents and maltreatment. As amply evidenced in this Bulletin, children’s exposure to violence is pervasive and crosses all ages. The research findings reported here are critical to informing our efforts to protect children from its damaging effects.