Paris taught French grammar in a private school, later succeeding his father as professor of medieval French literature at the Collège de France in 1872; in 1876 he was admitted to the Academy of Inscriptions and in 1896 to the Académie française; in 1895 he was appointed director of the Collège de France. He won a European reputation as a Romance scholar. He had learnt German methods of exact research, but besides being an accurate philologist he was a literary critic of great acumen and breadth of view, and brought a singularly clear mind to bear on his favourite study of medieval French literature. His "Vie de saint Alexis" (1872) broke new ground and provided a model for future editors of medieval texts. It included the original text and the variations of it dating from the 12th, 13th and 14th centuries. He contributed largely to the "Histoire littéraire de la France", and with Paul Meyer published "Romania", a journal devoted to the study of Romance literature.