The concept of the patient-centered medical home is gaining traction in debates about expanding access, improving quality, and restraining the cost of health care. These homes include physician-led multidisciplinary teams that provide comprehensive primary care, expanded hours (with possible open-access scheduling), integrated evidence-based quality measurement, better communication for the patient experience, and modern health information technology. The timing seems right in the United States and a proof-of-concept project has shown promising change.1 Yet concerns are being raised about slow uptake2 and whether this concept will withstand the test of health care reform.3 Some authorities suggest that the Ontario experience with medical homes could be a blueprint for reform in US primary care.4 Ontario offers tangible real-world lessons for both countries about the consequences of decisions made in the course of home construction.