To call Jim Steele "just" a veterinarian is like saying Bill Gates is "just" a software engineer. During his one hundred years of life, Steele changed the face of veterinary medicine and public health. As the first US assistant surgeon general for veterinary affairs at the Centers for Disease Control in Atlanta, he pioneered the simple but powerful philosophy that human health is intimately connected to the health of animals and our surrounding environment. His unwavering convictions, passion for medical progress, and strong leadership have saved and enriched countless human and animal lives. Animal Health Human Health One Health recounts Jim Steele's remarkable story, bringing to life his rough-and-tumble childhood in Chicago, his veterinary and academic career, countless battles with deadly diseases, public health adventures around the globe, creation of the first comprehensive scientific book series on zoonotic diseases, and his final years when he was still speaking, coauthoring scientific articles and books, and mentoring and advising students, colleagues and world leaders. He was the father of Veterinary Public Health and a motivator to all who met him. His life story is a great inspiration for anyone with curiosity and passion for the health, life and environmental sciences.