A B S T R A C TPurpose: Young adults have unique health and health care needs. Although morbidity and mortality stem largely from preventable factors, they lack a structured set of preventive care guidelines. The Affordable Care Act (ACA), enacted in 2010, increased young adult insurance coverage, prohibited copayments for preventive visits among privately insured and for many preventive services. The objectives were to evaluate pre-to post-ACA changes in young adults' past-year well visits and, among those using a past-year health care visit, the receipt of preventive services. Methods: We used pooled Medical Expenditure Panel Survey data, comparing pre-ACA (2007e2009, N ¼ 10,294) to post-ACA (2014e2016, N ¼ 10,567) young adults aged 18e25 years. Bivariable and multivariable stratified logistic regression, adjusting for sociodemographic covariates, were conducted to determine differences in well visits and in preventive services among past-year health care utilizers: blood pressure and cholesterol checks, influenza immunization, and all three received. Results: Past-year well visits increased from pre-ACA (28%) to post-ACA (32%), p < .001. Increases were noted for most demographic subgroups with greatest increases among males, Asian, and highest income subgroups. Larger pre-to post-ACA increases were found for most of the preventive services, p < .05, including the receipt of all three services (7% vs. 16%), p < .001, among past-year health care utilizers. Conclusion: Following ACA implementation, young adults experienced modest increases in well visit rates and larger increases in most preventive services received. Overall rates of both remain low. Building on these improvements requires concerted efforts that account for young adults' unique combination of health care issues and challenges in navigating an adult health care system.