Recent years have witnessed an upsurge in global health emergencies—from SARS to pandemic influenza to Ebola to Zika. Each of these occurrences has sparked calls for improved health preparedness. In Unprepared, Andrew Lakoff follows the history of health preparedness from its beginnings in 1950s Cold War civil defense to the early twenty-first century, when international health authorities carved out a global space for governing potential outbreaks. Alert systems and trigger devices now link health authorities, government officials, and vaccine manufacturers, all of whom are concerned with the possibility of a global pandemic. Funds have been devoted to cutting-edge research on pathogenic organisms, and a system of post hoc diagnosis analyzes sites of failed preparedness to find new targets for improvement. Yet, despite all these developments, the project of global health security continues to be unsettled by the prospect of surprise.