This study offers the first comprehensive analysis of the emergence of health care practitioners in Ontario. Patricia O'Reilly considers the whole range of Western health professionals, from medical psychologists to podiatrists, examining their roles and relationships in economic, political, judicial, educational, and interest group contexts.Health Care Practitioners takes as its focus the development of a new regulatory model, the Ontario Regulated Health Professions Act of 1991, and the extensive review of health practitioners that preceded it, namely, the Health Professions Legislation Review of 1983-9. This policy process, which highlighted the relationships that practitioners hold with each other, with the state, and with the public, is placed in both ideational and institutional contexts. Using an interpretive methodology, O'Reilly contrasts health-sector principles of self-governance, rationality, science, and technology with ideational principles of democracy, free-market enterprise, and judicial process. She looks at the emergence of various categories of practitioners, showing how legislative forces have worked to include, exclude, or marginalize them. Her narrative follows the evolution of the professions as a whole from a position of control and hierarchy to one of greater public accountability.