The federal budgeting process affects a wide range of people who work in public health, including those who work for government at local, state, and federal levels; those who work with government; those who operate government-funded programs; and those who receive program services. However, many people who are affected by the federal budget are not aware of or do not understand how it is appropriated or executed. This commentary is intended to give non–financial experts an overview of the federal budget process to address public health emergencies. Using CDC as an example, we provide: (1) a brief overview of the annual budget formulation and appropriation process; (2) a description of execution and implementation of the federal budget; and (3) an overview of emergency supplemental appropriations, using as examples the 2009 H1N1 influenza pandemic, the 2014-15 Ebola outbreak, and the 2016 Zika epidemic. Public health emergencies require rapid coordinated responses among Congress, government agencies, partners, and sometimes foreign, state, and local governments. It is important to have an understanding of the appropriation process, including supplemental appropriations that might come into play during public health emergencies, as well as the constraints under which Congress and federal agencies operate throughout the federal budget formulation process and execution.