The first principle is that violence is a process as well as an act; violent acts are often the culmination of long-term, identifiable problems, conflicts, disputes, and failures. Second, violence is produced by an interaction among three factors: the individual who takes violent action; triggering conditions that lead the subject to view violence as a "way out"; and a setting that facilitates the violence, or at least does not stop it from occurring. A third principle is that a key to investigation and resolution of threat-assessment cases is identification of the subject's "attack-related" behaviors. Fourth, threatening situations are more likely to be successfully investigated and managed if other agencies and systems are recognized and used to help solve problems presented by a given case. The three major functions of a threat-assessment program are the identification of a potential perpetrator, assessment of the risks of violence posed by a given perpetrator at a given time, and management of both the subject and the risks that he presents to a given target. Tactics and techniques for performing these three functions are discussed.