MOST AGREE ON THE NEED FOR RESTRUCTURING the US health care delivery system and increasing the capacity to provide coordinated care across the illness continuum in a patientcentered fashion. There is strong interest in developing accountable care organizations that have the capacities to (1) monitor meaningfully patient needs and outcomes, (2) use performance indicators for assessment of physicians and other professionals, and (3) implement new forms of reimbursement that result in improved quality while constraining increases in cost. A range of exemplary models are commonly used as examples including the Mayo Clinic, the Cleveland Clinic, Kaiser-Permanente, and Geisinger Health System but these examples are poorly matched to the existing distribution of medical practices and their small sizes. In 2005-2006, almost half of all physicians practiced by themselves or in partnerships and only 9% were in groups of 11 or more. Group organization in primary care was much the same. The notion that the organizational structures and cultures of the exemplary models can be replicated in even a decade seems unlikely. Major changes in reimbursement can expedite structural changes and aggregation of physicians into larger entities but changing the culture and developing new shared norms of professional responsibility and practice, effective teamwork, and an evidence-based and patientcentered perspective will be a more enduring challenge. Data from the Dartmouth Atlas and related studies suggest that many of these models offer care at more modest expenditure levels than typical of high-cost areas. As the advocacy and reasoning goes, transferring the successful approaches used by these settings will substantially improve care and lead to large savings that bend the cost curve downward. The problem is that an established approach for doing so is lacking, potentially leading to resistance and practical problems. A point often overlooked is that the culture of these exemplary centers and care systems developed over time (in some cases over a century or more), and in no case quickly; and the organizations that are admired are the successful entities, often with extraordinary leadership, and not those that failed or faltered along the way. In this mix, Kaiser Permanente is a relative newcomer, first sponsored by Kaiser industries in the late 1930s as an industrial health care program for their construction, shipyard, and industrial workers. Expenditures can be reduced by payment constraints on health care organizations and clinicians and by increasing patient cost sharing. But such crude constraints do not distinguish between appropriate and wasteful care seeking among patients. Nor do they prevent manipulation of reimbursement by health organizations and physicians such as risk avoidance, shifting responsibility to others, increasing volume, or up coding. The changes needed to realistically reorganize the provision of care requires reconstituting the norms and culture of the work of physicians and other professionals through their buy-in and centrality in change efforts.