This article aims to provide an intelligible explication of the doctrine of Transubstantiation. A model of this doctrine is formulated within the formal, neo-Aristotelian metaphysical and ontological framework of Jonathan Lowe, termed Serious Essentialism and the Four-Category Ontology. Formulating the doctrine of Transubstantiation within this metaphysical and ontological framework will enable it to be explicated in a clear and consistent manner, and the oft-raised intelligibility question against it can be answered.