A considerable amount of research on workplace violence has been conducted over the past two decades, resulting in a better understanding of its causes and consequences. Several models have been developed that consider the causes and consequences, as well as the organization's policies that influence workplace violence. The source of violence (internal vs. external), hierarchical position (supervisory vs. line positions), formalization in terms of policies, and the external environment factors that affect organizations have rarely been considered in combination with one another in models to date. The present paper develops a model addressing these gaps in the literature by incorporating these factors as influences on the likelihood of experiencing workplace violence. © 2011 Springer Science+Business Media, LLC.