With lessons learned from COVID-19, a world-leading expert on pandemic preparedness proposes a pragmatic plan urgently needed for the future of global health security. The COVID-19 pandemic revealed how unprepared the world was for such an event, as even the most sophisticated public health systems failed to cope. We must have far more investment and preparation, along with better detection, warning, and coordination within and across national boundaries. In an age of global pandemics, no country can achieve public health on its own. Health security planning is paramount. Lawrence O. Gostin has spent three decades designing resilient health systems and governance that take account of our interconnected world, as a close advisor to the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), and many public health agencies globally. Global Health Security addresses the borderless dangers societies now face, including infectious diseases and bioterrorism, and examines the political, environmental, and socioeconomic factors exacerbating these threats. Weak governance, ineffective health systems, and lack of preparedness are key sources of risk, and all of them came to the fore during the COVID-19 crisis, even—sometimes especially—in wealthy countries like the United States. But the solution is not just to improve national health policy, which can only react after the threat is realized at home. Gostin further proposes robust international institutions, tools for effective cross-border risk communication and action, and research programs targeting the global dimension of public health. Creating these systems will require not only sustained financial investment but also shared values of cooperation, collective responsibility, and equity. Gostin has witnessed the triumph of these values in national and international forums and has a clear plan to tackle the challenges ahead. Global Health Security therefore offers pragmatic solutions that address the failures of the recent past, while looking toward what we know is coming. Nothing could be more important to the future health of nations.