His thesis, Les cités de l'Afrique romaine au Bas-Empire, defended in 1977 under the direction of William Seston, profoundly changed the understanding of the urban world in the 3rd and 4th centuries; far from declining, the cities of Africa had some prosperity.
After his secondary education at lycée Charlemagne, he was received at the 1957 agrégation of history in 1957 and appointed to the University of Tunis between 1957 and 1959 before he did his military service in Algeria between November 1959 and January 1962.
Meanwhile, he took a stand against the Organisation armée secrète and wrote and distributed leaflets denouncing the abuses in the place to Le Canard Enchainé, which published his testimony.
President of the "Institut des études augustiniennes" between 1987 and 2000, he was also responsible for the 'Centre de recherches sur l’Antiquité tardive et le Haut Moyen-Âge'.
A member of the Comité des travaux historiques et scientifiques (Cths) in 1982, before becoming its secretary in 1992, a member of the Société des Antiquaires de France of which he was president in 2003 and president of the "Société française d’études épigraphiques sur Rome et le monde romain", Claude Lepelley was also publishing director of the series "Nouvelle Clio" from 1992 to 2008.