The absence of a comprehensive national playbook for developing and deploying testing has hindered the United States’ ability to rapidly suppress recent biological emergencies (for example, the COVID-19 pandemic and outbreaks of mpox). We describe here the Testing Playbook for Biological Emergencies, a national testing playbook we developed. It includes a set of decisions and actions for US officials to take at specific times during infectious disease emergencies to implement testing rapidly and to ensure that available testing meets clinical and public health needs. Although the United States had multiple plans at the federal level for responding to pandemic threats, US leaders were unable to quickly and efficiently operationalize those plans to deploy different types of tests during the COVID-19 pandemic in 2020–21, and again during the US mpox outbreak in 2022. The playbook fills a critical gap by providing the necessary specific and adaptable guidance for decision makers to meet this need.