This paper describes the attempts of the COHSE project to define and deploy a Conceptual Open Hypermedia Service. Consisting of

• an ontological reasoning service which is used to represent a sophisticated conceptual model of document terms and their relationships;
• a Web-based open hypermedia link service that can offer a range of different link-providing facilities in a scalable and non-intrusive fashion;

and integrated to form a conceptual hypermedia system to enable documents to be linked via metadata describing their contents and hence to improve the consistency and breadth of linking of WWW documents at retrieval time (as readers browse the documents) and authoring time (as authors create the documents).