More than 500,000 people in the US experience homelessness at any given time, many of whom now qualify for Medicaid in states that expanded coverage under the Affordable Care Act (ACA). In this article we use a novel data set from Arkansas to provide the first estimates of the association between gaining coverage through the ACA’s Medicaid expansion and health services use for a population experiencing homelessness. We find that Medicaid expansion was associated with large initial increases in inpatient hospitalizations and emergency department visits—which declined steadily over time—among adults experiencing homelessness compared with use by a sample of adult traditional Medicaid enrollees. Our results provide evidence of substantial pent-up demand for health care among a population experiencing homelessness in Arkansas that gained health insurance coverage as a result of Medicaid expansion.