There are few visible markers of the accomplishments of public health. When epidemiologists do their jobs, nothing happens. An outbreak does not grow into an epidemic. A child does not go hungry. A would-be smoker never lights up. In this fascinating window into the secret life of public health, Caitlin Rivers weaves together stories of triumph and tragedy to show that by making sure things don't happen, she and legions of scientists, practitioners, and policymakers change the course of history. We have many of the tools and experiences needed to prevent the next crisis, but as past experiences teach us, the unexpected is always around the corner. We cannot afford complacency, as countless challenges remain, including constantly emerging pathogens, the rapid growth of biotechnology, and the inconsistent cycles of funding for public health programs. Progress can be slow, but the unsung heroes in epidemiology remain focused on their missions. Crisis Averted tells their stories—from the eradication of smallpox in the twentieth century to a battle against mosquito-borne diseases in the Florida Keys to the international safeguards implemented against extraterrestrial germs. By taking a candid look at how we solve problems in public health, Caitlin Rivers illuminates the role of epidemiology in all our lives and lays out the case for what can be accomplished given sufficient vision, leadership, and resources. Crisis Averted is an inspiring and galvanizing call for us to work together towards a healthier, more resilient future.