In this paper, the author gives some preliminary examination of the ways in which an ontologyᎏan explicit specification of the conceptualization of the domainᎏcan support the verification and validation of a knowledge-based system. The discussion is focused on a simple, well-known, example relating to the identification of animals. Key elements of the support provided by the ontology relate to attempting to give coherence to the domain conceptualization; making the role of experts in verification and validation more structured and less at the mercy of interpretation; constraining the number of test cases required to give good coverage of the possible cases; and structuring the testing to give better assurance of its efficacy, and a possible basis for greater automation of the testing process. Finally, the author makes some concluding remarks.