Psychosocial factors refer to all organizational factors and interpersonal relationships in the workplace that may affect the health of the workers. Currently, two psychosocial risk models are universally recognized for producing solid scientific knowledge regarding the vital link between social or psychological phenomena at work and the development of several diseases, such as cardiovascular diseases or depression. The first is the "job demand-contro-support" model, which was defined by Karasek and to which the concept of social support has been added; the second is the "effort/reward imbalance" model defined by Siegrist. The public health perspective calls for theoretical models based on certain psychosocial attributes of the work environment for which there is empirical evidence of their pathogenic potential for exposed workers. Not only do these models reduce the complexity of the psychosocial reality of the work to components that are significant in terms of health risks, but they also facilitate the development and implementation of workplace interventions. Psychosocial risk intervention strategies currently implemented by companies are predominantly individual-oriented and aim chiefly at reducing the effects of stressful work situations by improving individual ability to adapt to the situation and manage stress. Like personal protection equipment for exposure to physical or chemical risks, these secondary prevention measures are commendable but insufficient, because they aim to reduce only the symptoms and not the cause of problems. Any intervention program for these risks should necessarily include a primary prevention component with a view to eliminating, or at least reducing, the psychosocial pathogenic agents in the workplace. Several authors have suggested that well-structured organizational approaches are most effective and should generate more important, longer-lasting effects than individual approaches. However, the evidence should be strengthened by more systematic studies to assess the models, their implementation and the outcomes for employers and employees alike. The research agenda on mental health and the workplace should have the following goals; to foster the development and evaluation of well-adapted models of interventions designed to reduce adverse psychosocial factors and their mental health effects to give a better understanding of the prevalence of work organization risk factors in Canada, how they may be changing and how they affect mental health in the long term to acquire an understanding of the effects on mental health of prominent trends in organizational practices, such as restructuring, lean production and flexible staffing (all of which result in precarious employment), that may pose special risks for women, immigrants or aging workers in Canada to collect data on the considerable direct and indirect costs to business, workers and society of work-related stress in Canada.