This is a systematic review of literature published since 1992, to determine the effectiveness of interventions in preventing workplace violence and to suggest interventions that need further evaluation research. The health care industry is the topic of 54% of the papers, the retail industry is the topic of 11% of the papers, and the remaining papers address the workplace in general or other situations. This finding drives the organization of this review: the first group of papers discussed in this review evaluates interventions to prevent workplace violence in the retail industry - mostly to prevent robbery and violence to retail workers. Singly or in combination, environmental designs in the retail industry, such as increased lighting to improve visibility and a limited cash-handling policy, can make workers safer, but more research is needed to overcome the barriers to implementation of environmental designs, especially in small businesses. The second group of papers in this review is about interventions to prevent violence to health care workers - mostly training and techniques of dealing with combative patients. Training health care workers to better cope with violent patients and to avoid injury is becoming standard practice, but research is needed to identify specific aspects of training and patient management programs that are most effective.