Despite growth in private equity (PE) acquisitions of physician practices in the US, little is known about how changes in ownership influence workforce composition. Using clinician-level data linked to practice acquisition information, we estimated changes in clinician workforce composition in PE-acquired practice sites relative to non-PE-acquired independent practice sites for dermatology, ophthalmology, and gastroenterology specialties. We calculated a clinician replacement ratio (cumulative number of entering clinicians during 2014-19 divided by the cumulative number of exiting clinicians) across 213 PE-acquired practices and 995 matched non-PE-acquired practices. Using a difference-in-differences approach, we also examined practice-level changes in yearly clinician counts at PE-acquired practices before and after acquisition compared with non-PE-acquired controls. In aggregate and across the study period, the clinician replacement ratio was higher for PE-acquired practices compared with non-PE-acquired controls (1.75 versus 1.37), as well as within each specialty and clinician type (physician versus advanced practice provider). Relative to non-PE-acquired control practices, we also found significant yearly increases in the number of advanced practice providers at PE-acquired practices after acquisition. Taken together, these findings suggest differential changes in workforce composition at PE-acquired practices, especially a shift toward advanced practice providers for care delivery.