Abstract. WordNet is an electronic lexical database structured around psychological and linguistic principles. As such, it should play a part in any e ort to integrate cognitive factors into knowledge based systems. Yet, some of its basic assumptions have been attacked, and the suggestion made that a major restructuring would make it more cognitively transparent. We investigate these allegations from a psycholinguistic perspective and conclude that WordNet is in fact rigorous in terms of the cognitive principles it embodies. What is lacking is a methodology for translating the explicit and implicit knowledge in WordNet into a usable, formal ontologies. We show some ways in which WordNet should be extended to facilitate this process. We agree that WordNet is not in itself ready for use as a formal ontology, but we argue that it is an invaluable tool for describing the conceptualized structure of our world, and should be used as a fundamental resource. 1