OBJECTIVE: To describe and explain self-reported trends in patient demand, clinic capacity, and the availability of donated goods and volunteer services in free and charitable clinics (FCCs) after the Affordable Care Act (ACA). BACKGROUND: FCCs, which are nonprofits that utilize volunteers and donations to provide healthcare services to low-income uninsured and medically underserved at no cost or a small fee, are adjuncts to the formal safety net. Examining trends among FCCs after the ACA is instructive because FCCs’ experiences help clarify their role and can serve as a barometer of the ACA’s success. Because states had the option to expand Medicaid up to 138% of poverty, comparing FCCs’ experiences in expansion states versus FCCs in nonexpansion states can reveal how FCCs deal with coverage expansions. It is predicted that the ACA would reduce patient demand at FCCs, especially in Medicaid expansion states. METHODS: Data are derived from a one-of-a-kind dataset of approximately 850 FCCs responding to a national survey of all known FCCs (~1,500) in 2015-2016. RESULTS: More FCCs reported decreases in patient demand in expansion states than in nonexpansion states (43% vs. 18%, p<.001). Similarly, more FCCs in expansion states reported reducing hours (14%) or services (8%), compared with FCCs in nonexpansion states (5% and 2%, respectively, p<.01). Concomitantly, a higher percentage of FCCs in expansion states reported decreases in donated labs and other diagnostics (21% vs. 11%, p<.01), donated medicines (26% vs. 22%, p<.10), and volunteer providers (22% vs. 15%, p=.052). DISCUSSION: While more FCCs in expansion reported decreases in demand, capacity, and resources, they are nonetheless a minority. CONCLUSION: Even in Medicaid expansion states, the demand for care from FCCs has persisted. Furthermore, FCCs have been able to maintain their capacity during times of uncertainty and heightened resource constraints, illustrating the enduring nature of the FCC model.