Different staffing configurations in primary and geriatric care practices could have implications for how best to deliver services that are essential for a growing population of older adults. Using data from a 2018 survey of physicians (MDs) and nurse practitioners (NPs) working in primary and geriatric care, we assessed whether different configurations were associated with better or worse performance on a number of standard process measures indicative of comprehensive, high-quality primary care. Practices with a large concentration of MDs had the highest estimated labor costs. Practices high in NPs and physician assistants (PAs) were most common in states that grant full scope of practice to NPs. The high-NP/PA configuration was associated with a 17-percentage-point greater probability of facilitating patient visits and a 26-percentage-point greater probability of providing the full bundle of primary care services compared with the high-MD model. Team-based configurations had a 27.7-percentage-point greater probability of providing the full bundle of primary care services. The complex needs of older adults may be best served by team-based practices with a broad provider mix that can provide a range of services in the office and the community.