Born in the village of Neuville near Beauvais, in Picardie. His parents could only afford to send him to a small school in the village, but he picked up some Latin from the friars of a neighbouring convent, who brought him under the notice of the bishop of Beauvais. By his kindness Baillet received a thorough education at the theological seminary, and was afterwards appointed to a post as teacher in the college of Beauvais. In 1676 he was ordained priest and was presented to a small vicarage. He accepted in 1680 the appointment of librarian to François-Chrétien de Lamoignon, advocate-general to the parlement of Paris, of whose library he made a catalogue raisonnd (35 vols.), all written with his own hand. The remainder of his life was spent in incessant, unremitting labour; so keen was his devotion to study that he allowed himself only five hours a day for rest.
Of his numerous works the following are the most conspicuous:
See the edition by M. de la Monnoye of the Jugemens des savans (Amsterdam, 4. vols. 1725), which contains the Anti-Baillet of Gilles Ménage and an Abre’ge de la vie de Mr Baillet.