Primary care access in Medicaid improved after the Patient Protection and Affordable Care Act despite millions of new beneficiaries. One possible explanation is that practices are scheduling more appointments with advanced practitioners. To test this theory, we used data from a secret shopper study in which callers simulated new Medicaid patients and requested appointments with 3,742 randomly selected primary care practices in 10 states. Conditional on scheduling an appointment, simulated patients asked whether the practitioner was a physician or advanced practitioner. From 2012 through 2016, the proportion of appointments scheduled with advanced practitioners increased from 7.7% to 12.9% ( P <.001) across the 10 states.