Enrollment of young adults is foundational to the success of the Affordable Care Act (ACA). This article analyzes the implications for young adults transitioning from pediatric to adult care with the implementation of the ACA. We review the key characteristics of this population relevant to health care utilization and access as well as the impact of private insurance market reforms, health insurance marketplaces, Medicaid expansion, and workforce development provisions on this population. We then analyze how reform is impacting and will continue to impact specific populations of young adults, including individuals with disabilities, college students, immigrants, young adults who age out of the foster care system and individuals involved with the criminal justice system. Finally, we look at the socio-economic and political factors influencing outreach efforts, and make recommendations to maximize the benefits of the law for young adults to empower them to have access to care and financial security.