Scope-of-practice regulations, including prescribing limits and supervision requirements, may influence the propensity of providers to form care teams. Therefore, policy makers need to understand the effect of both team-based care and provider type on clinical outcomes. We examined how care management and biomarker outcomes after the onset of three chronic diseases differed both by team-based versus solo care and by physician versus nonphysician (that is, nurse practitioner and physician assistant) care. Using 2013-18 deidentified electronic health record data from US primary care practices, we found that provider teams outperformed solo providers, irrespective of team composition. Among solo providers, physicians and nonphysicians exhibited little meaningful difference in performance. As policy makers contemplate scope-of-practice changes, they should consider the effects of not only provider type but also team-based care on outcomes. Interventions that may encourage provider team formation, including scope-of-practice reforms, may improve the value of care.