The proposed threat assessment process derives from the findings of a previous study of targeted school attacks and their perpetrators. It found that before the attacks, other students had observed attacker behaviors and heard comments that suggested they might be planning the attack. The threat assessment process is a means of identifying students who show warning signs for violent behavior, assessing their level of risk, and then deciding what action should be pursued. Authorities involved in conducting a threat assessment should gather and analyze information on the behavior and comments of the identified student. This information, in turn, will permit the authorities to make reasonable judgments about whether the subject of the assessment is on a path toward an attack on an identifiable target. Three elements are essential to the development and operation of an effective school-based threat assessment program: the authority to conduct an assessment, the capacity to conduct inquiries and investigations, and integrated systems relationships. The latter element requires building relationships among individuals and organizations both within and outside the school. These relationships can help the threat-assessment team acquire and use information about a given situation and individual. This guide provides suggestions for implementing each of the three features of a threat assessment. This guide also presents action plans for school leaders in creating a safe and connected school climate and implementing a threat assessment program. A 24-item annotated bibliography