A review of attempts to define violence and an analysis of data from current research on workplace violence suggest that a comprehensive definition of workplace violence should include at least references to the target, source, perception of the act, impact, and relationship to places of work. Further, without a comprehensive typology of workplace violence, the research focus may be too narrow and attempts to identify and manage such violence too limited. A widely used classification mentioned in research on workplace violence is the typology developed by the Californian Division of Occupational Safety and Health. This original schema identifies three types of workplace violence that the current paper calls "intrusive," "consumer-related," and "relationship." To these categories of workplace violence, the author adds "organizational" violence. The author identifies subcategories for the four types of workplace violence. "Intrusive" violence includes criminal intent by strangers, terrorist acts, mental illness or drug-related aggression, and protest violence. "Consumer-related" violence encompasses consumer/clients/patients (and family) violence against staff, vicarious trauma to staff, and staff violence to clients/consumers. "Relationship" violence includes staff-on-staff violence and bullying and domestic violence at work. "Organizational" violence involves organizational violence against staff and organizational violence against consumers/clients/patients. It may be important to clarify the nature of the work-related duties that lead to involvement in violence, compared to a worker-victim who just happens to be in a situation where violence occurs. These issues are important in the context of legal proceedings occasioned by workplace violence. 45 notes