Prior research on consultants in policymaking described their expanding policy involvement and impact. This research focuses on consultants' policy formulation roles and on how and why these roles vary across jurisdictions and contexts. It draws on comparative research on healthcare policy in Ontario, Canada, and Victoria, Australia. Based on analysis of contracts and expenditure data, and 59 semi-structured interviews, this research finds that consultants in Victoria are partners in formulation, used routinely for a variety of tasks, including core formulation work. Their role is institutionalized through formal and informal rules. In contrast, consult- ants in Ontario perform non-core formulation work and are primarily active in linking the government to other sites and pools of knowledge. The paper ties this variation to public sector internal capacity and policy sector complexity. It offers new empirical data and provides a nuanced understanding of the roles of consultants in policy formulation.