The National Academies of Sciences, Engineering, and Medicine held a workshop on August 22-23, 2018, in Washington, DC, to explore medical and public health preparedness for a nuclear incident. The event brought together experts from government, nongovernmental organizations, academia, and the private sector to explore current assumptions behind the status of medical and public health preparedness for a nuclear incident, examine potential changes in these assumptions in light of increasing concerns about the use of nuclear warfare, and discuss challenges and opportunities for capacity building in the current threat environment. This publication summarizes the presentations and discussions from the workshop.Table of ContentsFront Matter1 Introduction2 Federal Planning for Nuclear Incidents3 Current State of Nuclear Preparedness4 Updating Planning Assumptions of Nuclear Preparedness5 Implications of Communication, Education, and Information Challenges6 Challenges for Building Capacity Within the Health Care System7 Capability-Building Challenges and Opportunities: Building Response Capability8 Capability-Building Challenges and Opportunities: Ensuring Workforce Readiness and Response Capacity9 Building Preparedness and Response Capability: Looking to the Future10 Reflections on the Workshop and Opportunities for Moving ForwardReferencesAppendix A: Workshop AgendaAppendix B: Workshop Speaker Biographies