— In this paper I show how ontologies support the student modelling through the semantic definition of concepts that depict a student. The aim is to outline the framework for building ontologies as knowledge repositories. The advantages stemmed from the design and the use of ontologies are quite valuable, such as: the formal representation of knowledge based on axioms; the inferences outcome from inheritance relations; the easy-readable ontology’s code for humans and machines; and the provision of federative services for ontology management through agents. Hence, as a result of the experiment that was fulfilled in a Web based education system (WBES), I found out that ontologies provide a solid and reliability support for depicting attributes that concern to an individual, who is represented by a student model (SM). Keywords— Student modelling, student model, ontologies, Web based education systems