Only in several controlled studies have organizational or situational stressors (in contrast to individuals) been targeted for change in order to reduce occupational stress. This study evaluates the impact of an intervention which was based on organizational development, action research and Karasek's job strain model. Employee committees conducted problem diagnosis, action planning, and action taking in two departments in a public agency. Waiting list control departments and pre‐ post‐ and follow‐up assessment were utilized. Results indicated a mixed impact of the intervention in one department, but a negligible or negative impact in the other. Obstacles to the effective implementation of the intervention strategy are discussed. These included a limited focus for the committees (department‐wide rather than agency‐wide), the negative impact of a major agency reorganization, and the lack of a more formal management and labour commitment to maintaining the stress reduction and organizational change process.