With the 2001 anthrax attacks, the threat of bioterrorism became real to the nation. Before that, biological weapons were a known threat to warfighters, but after, the vulnerability of US civilians was clear. It was also clear that the US government was not organized to address the national security and civilian threat of bioweapons. Only a handful of civilian experts were involved, and the Alfred P. Sloan Foundation was the only US philanthropy willing to commit resources to confront the challenges of preparing for bioterorism. When Sloan got involved in 2000, the professional field of biosecurity did not exist. There was little science or scholarship no guidelines or planning tools, and few policies or officials to direct civilian preparedness, planning, and response. Over ten years, the Sloan Foundation awarded more than $44 million in biosecurity grants and was instrumental in establishing the field and many of its most prominent leaders. That was money well-invested. The nation is now vastly better prepared for bioterrorism and other catastrophic threats to the public’s health and national security. Author Gigi Kwik Gronvall chronicles the foundation’s leadership in the field and the innovations that followed to show how the Sloan Foundation helped lay the groundwork on which US civilian biosecurity has been built.