Sullivan was born and raised in Medfield, Massachusetts, a suburb of Boston. He earned a BA in English from Hamilton College in 1980. After graduating, he served as a volunteer in the Peace Corps, teaching English to children of Tuareg nomads in the Saraha Desert. Sullivan returned to the United States in 1982 and studied at the Medill School of Journalism of Northwestern University in Chicago. He began writing fiction at 30 and his first novel, The Fall Line (1994), was a New York Times Notable Book of the Year.