More than 83 million people in the United States live in primary care shortage areas. As the US healthcare system faces a contracting primary care physician workforce, advanced practice providers are playing an increasingly important role in the delivery of primary care services. In parallel, public discourse regarding the differences in care delivery by advanced practice providers versus physicians has also expanded. In this commentary, we describe 3 main evidence gaps hindering optimal physician and advanced practice provider work organization in contemporary primary care delivery: (1) gaps in understanding the unique and overlapping competencies of each role group, (2) gaps in evaluating and defining optimal role delineation, and (3) gaps in payment models supporting effective collaboration. We subsequently present key needs in these 3 areas, including technology-based approaches to track physician and advanced practice provider competencies, increased empirical data on different clinical teaming structures, and exploration of novel models for primary care payment. We also note the need for an enhanced understanding of patient perspectives regarding primary care role types and teaming structures.