Jack Gantos was born in Mount Pleasant, Pennsylvania. His parents moved so often that he attended 10 different schools between kindergarten and 12th grade. The Gantos family rented a variety of homes in Pennsylvania, Florida, North Carolina, and the Caribbean. Jack spent his senior year of high school in Florida after his parents had already moved to Puerto Rico. During that year, Gantos worked at a grocery store, bought a car, and lived in an old motel run by Davey Crockett's great-great granddaughter.