<p>If associations include multiple constituencies with conflicting preferences, whose preferences will they represent? We argue that the higher the territorial level of policy-making authority in a polity, the more influence the resource-rich constituencies will have on an association’s policy positions. We apply this argument to the contrasting positions over medical remuneration taken by the medical associations in two federal countries, Australia and Canada between the 1960s and the 1990s. In Australia, organised medicine consistently took elitist positions that increased the income gap between the highest and lowest paid medical disciplines. Conversely, the Canadian medical associations took solidaristic positions that aimed to reduce that gap. This difference reflects the greater centralisation of healthcare policies in Australian compared to Canada. Moreover. the impact of healthcare policy centralisation has been reinforced by the stratarchical organisation of Australian medicine, suggesting a connection between the literature on interest groups and that on the multi-level organisation of political parties.</p>