AbstractResearch has documented how the decline in professional self-regulation in the UK and Australia was led by policy-makers in response to regulatory failures. In Canada, professional self-regulation is currently in decline as well, and while policy-makers have driven some change it is also the case that self-regulating professions have begun to transform themselves from within: altering their structure, make-up, and processes to enhance fairness, public input, and accountability, while reducing professional control. Why would they do so? This paper draws on the concept of institutional isomorphism to understand why professional regulators would invoke changes that, on the surface, might seem to counteract their own interests. Analysing data from 46 interviews with leaders in healthcare profession regulation, this paper examines how coercive, mimetic, and normative processes drive regulatory reform in a changing regulatory field.