This paper presents a quality ontology that formalizes all the needed knowledge for the realization of a multi-perspective and adaptive evaluation of e-government services. Different perspectives are taken into account and the mappings between them are defined using the presented ontology, enabling a comprehensive and holistic view of quality. Based on the quality ontology presented, the evaluation can be organized in a way to serve every citizen individually, increasing the efficiency of e-government services’ evaluation. The quality ontology can form the basis for the future construction of an ontology-based system which implements the customized and multi-perspective assessment of public e-services.