Commissioned to mark the 50th anniversary of the National Academy of Medicine (NAM; formerly the Institute of Medicine [IOM]), this volume describes the circumstances that led to the IOM's founding in 1970, the members and leaders who built and sustained the organization, and the process by which the IOM became the NAM in 2015. The volume also details a selection of the IOM/NAM's most influential contributions to biomedical science, U.S. health care, and population health and concludes with the story of how the organization navigated unprecedented national and global crises between 2015 and 2021.