This paper revisits the purposes and achievements of regionalization, a decade after its widespread implementation across Canada, and considers to what extent changes in healthcare concepts, emphasis and delivery can reasonably be attributed to it. The authors address four main questions. What, conceptually, is regionalization in healthcare, and what distinguishes it as a structure? How was regionalization intended to contribute to the achievement of the goals for the health system articulated in the 1980s and 1990s? How has regionalization been implemented in Canada, and how have these factors affected its potential to achieve its intended impact? And finally, with the experience gained over the last decade, how might we now (re)design regionalization to better contribute to health system goals? In Canada, regionalization of healthcare has entailed more than devolution and decentralization of services from provincial governments to regional authorities. It included consolidation of authority from local boards and agencies, and some centralization of services. Regionalization was the remedy proposed for the diagnosis of fragmentation and incoherence made by commissions across the country in the 1980s. Regionalization addressed the organizational dimensions of the perceived problems, but provincial governments added goals unrelated to structural change to its mandate. The authors assess the potential impact of regionalization on health system goals and take stock of current Canadian circumstances. Even where regionalization's impact is theoretically high, there are many practical limits to its effect. Although it can facilitate or impede change, in the end the will and actions of provincial governments, providers and other actors in the health system are fundamental to attaining more substantive goals. Many health reform goals require nothing less than a transformation of how society views health, and in the culture of healthcare delivery. Further, the authors argue that the implementation of regionalization in Canada has been limited. Devolution has typically been halting and provisional; there has been little stability; and there have been constraints on the ability to act. These limitations have reduced its potential effect. The authors conclude with proposals for increasing regionalization's contribution to health reform goals. These include a more stable and transparent provincial-RHA relationship, information and measures to better align resources to needs, increased regional-level system integration and changes to organizational culture and practice in the health system.