The Patient-Centered Medical Home (PCMH) now defines excellent primary care. Recent literature has begun to elucidate the components of PCMHs that improve care and reduce costs, but there is little empiric evidence that helps practices, payers, or policy makers understand how high-performing practices have improved outcomes. We report the findings from 38 such practices that fill this gap. We describe how they execute 8 functions that collectively meet patient needs. They include managing populations, providing self-management support coaching, providing integrated behavioral health care, and managing referrals. The functions provide a more actionable perspective on the work of primary care.