 Robert Alyngton was one of the most important authors of the generation after John Wyclif. He was deeply influenced by Walter Burley’s logico-ontological system and Wyclif’s metaphysics. His major extant work, a commentary on the Categories, heavily depends on Burley’s last commentary on the Categories and Wyclif’s De ente praedicamentali. Yet he was able to develop new logical and semantic theories as well as the general strategy adopted by the Oxford Realists, as he methodically substituted reference to external objective realities for reference to linguistic and/or mental activities.