PURPOSE: The patient-centered medical home is often discussed as though there exist either traditional practices or medical homes, with marked differences between them. We analyzed data from an evaluation of certified medical homes in Minnesota to study this topic. METHODS: We obtained publicly reported composite measures for quality of care outcomes pertaining to diabetes and vascular disease for all clinics in Minnesota from 2008 to 2010. The extent of and change in practice systems over that same time period for the first 120 clinics serving adults certified as health care homes (HCHs) was measured by the Physician Practice Connections Research Survey (PPC-RS), a self-report tool similar to the National Committee for Quality Assurance standards for patient-centered medical homes. Measures were compared between these clinics and 518 non-HCH clinics in the state. RESULTS: Among the 102 clinics for which we had precertification and postcertification scores for both the PPC-RS and either diabetes or vascular disease measures, the mean increase in systems score over 3 years was an absolute 29.1% (SD = 16.7%) from a baseline score of 38.8% (SD = 16.5%, P =.001). The proportion of clinics in which all patients had optimal diabetes measures improved by an absolute 2.1% (SD = 5.5%, P =.001) and the proportion in which all had optimal cardiovascular disease measures by 4.4% (SD = 7.5%, P =.001), but all measures varied widely among clinics. Mean performance rates of HCH clinics were higher than those of non-HCH clinics, but there was extensive overlap, and neither group changed much over this time period. CONCLUSIONS: The extensive variation among HCH clinics, their overlap with non-HCH clinics, and the small change in performance over time suggest that medical homes are not similar, that change in outcomes is slow, and that there is a continuum of transformation.