T here were almost one million "small" businesses (SBs)* in Canada in 2004. 1 These enterprises, often defined as those employing fewer than 50 persons, include over 4 million workers, about 39% of the private labour force. 1 Industries dominated by small businesses tend to have higher fatality rates than do industries dominated by larger-sized organizations, 2 and they present enduring, unresolved challenges to the occupational health and safety (OHS) system in terms of prevention, disability and return to work.Internationally, small workplaces are widely considered hard to reach in terms of health and safety regulation and service 3,4 and relatively impervious to the regular tools of the trade for assessing risk, providing service and designing interventions. To improve OHS in small firms, research and practice have concentrated on linking the level of risk to attributes of the workplace and those who work there, including the risk profiles of workers (e.g., higher risk groups like immigrants and young people are disproportionately employed in this sector) or the deficits of management (e.g., employers may lack the resources, knowledge, skills, time and motivation to deal effectively with OHS). 5 Associated with this definition of the problem are intervention approaches that are educational or motivational in nature (e.g., informing employers of obligations and risks, offering financial incentives for prevention activities) and that are of low cost, simplified and industry specific. Service delivery has been adapted to the small workplace situation, for example, through the introduction of more appropriate measurement tools, 6 more understandable and relevant educational materials, 7 upgraded management systems 8,9 and special modes of consultation, such as those involving safety representatives, worker participation 10,11 and intermediaries. 12,13 More recently, attention has moved upstream, in the sense of McKinlay's iconic notion of upstream-downstream thinking: 14 searching for cause and locating intervention further from the most immediate local site of the phenomenon. An upstream perspective on small workplace health focuses on broad contextual influences (e.g., economic systems, structure of labour markets 15 and organizational/regulatory arrangements such as subcontracting 16 and outsourcing 17 ) and on intermediate structures and processes (e.g., the institutions, programs and professional service providers of the OHS system itself). An upstream perspective focuses less on the problematic features of small workplaces than on the conditions that set the terms for and influence such problems. 18 The purpose of this paper is to contribute to an upstream perspective on OHS in small workplaces and thereby to advance our understanding of why small workplaces are the way they are and of