The oo CIDOC Reference Model represents an ontology; i.e. it describes in a formal language the overt and implicit concepts and relations relevant to cultural heritage information. The authors argue that the semantic and structural incompatibility of existing information systems constitutes a major barrier to integration. An ontology such as the CIDOC Reference Model can serve as a basis for mediation of cultural heritage information and thereby provide the semantic 'glue' needed to transform today's disparate, localised information sources into a coherent and valuable global resource. After a discussion of museums' communication needs, the authors position the role of a reference model with respect to the major projects in the field before presenting the principles features of the CIDOC reference model along with examples of its application. They conclude with some ideas for future development. 1. Introduction The creation of the World Wide Web has had a profound impact on the ease w..