As the United States continues to adapt to a more digital, mobile, and interconnected world, health care and public health professionals have sought to better prepare for and respond to long-standing and emerging threats to the nation's health security. Health security is the collective effort to prevent, protect against, mitigate, respond to, and recover from the health consequences of natural, man-made, and technological disasters. Although substantial progress has been made in the past 15 years toward improving health care and public health systems and capacities for health security threats, many complex challenges persist, and often the nation's preparedness efforts are not sufficient. On March 8-9, 2017, the National Academies of Sciences, Engineering, and Medicine's Forum on Medical and Public Health Preparedness for Disasters and Emergencies hosted a two-day public workshop to acknowledge these persistent issues; to evaluate past, and perhaps inadequate, approaches to addressing them; and to discuss intentional and innovative new solutions. This publication summarizes the presentations and discussions from the workshop.Table of ContentsFront Matter1 Introduction2 A Brief Overview of Health Security Threats and Programs3 Proposed Priorities and Persistent Challenges Related to Health Security4 Underlying Issues in Health Security5 Potential Strategies for Strengthening the Nation's Health Security6 Future OpportunitiesReferencesAppendix A: Workshop AgendaAppendix B: Statement of TaskAppendix C: Biographical Sketches of Workshop Speakers and Moderators