Why would a student bring a weapon to school and without any explicable reason open fire on fellow students and teachers? Are school shooters angry? Are they crazy? Is their motive revenge? Hatred for the victims? A hunger for attention? The origins of human violence are complex. Thinkers, historians, and scientists have explored the issue for centuries, but answers remain elusive. The roots of a violent act are multiple, intricate, and intertwined. The mix of factors varies according to the individual and the circumstances. Understanding violence after it has occurred is difficult enough. Trying to assess a threat and keep it from being carried out is even more of a challenge. This monograph presents a systematic procedure for threat assessment and intervention. The model is designed to be used by educators, mental health professionals and law enforcement agencies. Obviously, the same events that led the National Center for the Analysis of Violent Crime (NCAVC) to this subject have also led school administrators and law enforcement officials across the country to consider and develop their own policies and procedures for dealing with threats or acts of violence in schools. This model is offered in the hope that it may help refine and strengthen those efforts. Its fundamental building blocks are the threat assessment standards outlined in Chapter II, which provide a framework for evaluating a spoken, written, and symbolic threat, and the four-pronged assessment approach, which will be described in Chapter III and provides a logical, methodical process to examine the threatener and assess the risk that the threat will be carried out. This model is not a "profile" of the school shooter or a checklist of danger signs pointing to the next adolescent who will bring lethal violence to a school. Those things do not exist. Although the risk of an actual shooting incident in any one school is very low, threats of violence are potentially a problem in any school. Once a threat is made, having a fair, rational, and standardized method of evaluating and responding to threats is critically important.