Lisa A. Cooper, MD, MPH; Joshua M. Sharfstein, MD; Rachel L. J. Thornton, MD, PhD The American Rescue Plan Act of 2021 (ARPA), a $1.9 trillion economic stimulus bill, was signed into law by President Biden on March 11, 2021. 1 Although the bill largely focused on the devastation related to the COVID-19 pandemic, the ARPA is also poised to effectuate a momentous expansion of the Patient Protection and Affordable Care Act (ACA). 2 With an eye toward increasing access to health care and bolstering affordability, the ARPA expands health insurance marketplace subsidies, defrays the health insurance costs of the unemployed, and incentivizes nonexpansion states to expand their Medicaid programs to all low-income adults.