Confidence is increasing that the patient-centered medical home model of primary care can be a strong foundation for a high-performing US health care system. The medical home concept was first described in 1967 by the American Academy of Pediatrics, and medical homes have been demonstrated as the most effective way to care for children with special needs.1 Less is known about the model's effectiveness in caring for patients of all ages. There is robust evidence that primary care–based systems produce higher quality at more affordable costs2 and help to level health disparities that come with social disadvantage. But the United States does not have a viable primary care–based health care system.