Many of the elements of the Affordable Care Act (ACA) went into effect in 2014, and with the establishment of many new rules and regulations, there will continue to be significant changes to the United States health care system. It is not clear what impact these changes will have on medical and public health preparedness programs around the country. Although there has been tremendous progress since 2005 and Hurricane Katrina, there is still a long way to go to ensure the health security of the Country. There is a commonly held notion that preparedness is separate and distinct from everyday operations, and that it only affects emergency departments. But time and time again, catastrophic events challenge the entire health care system, from acute care and emergency medical services down to the public health and community clinic level, and the lack of preparedness of one part of the system places preventable stress on other components. The implementation of the ACA provides the opportunity to consider how to incorporate preparedness into all aspects of the health care system. The Impacts of the Affordable Care Act on Preparedness Resources and Programs is the summary of a workshop convened by the Institute of Medicine's Forum on Medical and Public Health Preparedness for Catastrophic Events in November 2013 to discuss how changes to the health system as a result of the ACA might impact medical and public health preparedness programs across the nation. This report discusses challenges and benefits of the Affordable Care Act to disaster preparedness and response efforts around the country and considers how changes to payment and reimbursement models will present opportunities and challenges to strengthen disaster preparedness and response capacities.