Summary Violence in the workplace, particularly between members of the same organization, has impacts on the personnel’s health and safety. While Québec has instituted a legislative framework for addressing this phenomenon, the usefulness and effectiveness of the means used for its prevention are not well known. The authors conducted a study with correctional service agents in three detention institutions, where the researchers had previously shown that organizational factors were associated with this issue. This study was based on a participatory approach that they systematically evaluated using a well-known model. In fact, it involved an intervention that was based on the employees and their superiors determining the organizational constraints that cause the violence and the solutions for stopping and preventing it. The workers’ participation in the process helped establish a new dynamic. The authors noted a change in attitude in several of the actors who were directly or less directly affected by the study, mainly in the intervention support groups, the coordination group and the follow-up committee, which had the main responsibility of dealing with the question of the problems related to disrupted social relationships. The authors emphasize the significance of labour/management representation and participation, which were the cornerstones of the entire intervention process. More generally, the study identified organizational practices that promote a reduction in violence between members of the same organization.