The National Cancer Policy Forum of the National Academies of Sciences, Engineering, and Medicine convened a virtual public workshop on March 1-2, 2021 to examine the impact of the Affordable Care Act (ACA)on cancer prevention and care. Workshop participants discussed the available evidence to assess (1) the effects of the ACA on people at risk for or living with cancer and (2) lessons learned from the ACA's design and implementation, looking to inform future efforts to improve and support the delivery of high-quality and equitable cancer care across the care continuum. Additionally, participants discussed new models of payment for cancer care delivery as well as the impact of new organizational infrastructures made possible by the ACA to help patients and health care consumers make better informed health care choices. A number of workshop participants spoke about patient protections provided by the ACA and their implications for the care of people diagnosed with cancer. This Proceedings of a Workshop provides a high-level summary of the discussions presented during the workshop.