Natural disasters, infectious disease epidemics, terrorism, and major events like the nuclear incident at Fukushima all pose major potential challenges to public health and security. Events such as the anthrax letters of 2001, Hurricanes Katrina, Irene, and Sandy, severe acute respiratory syndrome (SARS) and West Nile virus outbreaks, and the 2009 H1N1 influenza pandemic have demonstrated that public health, emergency management, and national security efforts are interconnected. These and other events have increased the national resolve and the resources committed to improving the national health security infrastructure. However, as fiscal pressures force federal, state, and local governments to examine spending, there is a growing need to demonstrate both what the investment in public health preparedness has bought and where gaps remain in our nation's health security. To address these needs, the Association of State and Territorial Health Officials (ASTHO), through a cooperative agreement with the Centers for Disease Control and Prevention (CDC) Office of Public Health Preparedness and Response (PHPR), is creating an annual measure of health security and preparedness at the national and state levels: the National Health Security Preparedness Index (NHSPI). "In the past year, I have been struck by how important measurement is to improving the human condition. You can achieve incredible progress if you set a clear goal and find a measure that will drive progress toward that goal. ..." -Bill Gates 1 "What gets measured gets done." -Peter Drucker 2.