This workshop will first review the structure of thesauri and ontologies: - facets - hierarchy - richer relationships. Next, it will give several examples how thesauri and ontologies using richer relationships can be used to improve retrieval of documents and data on the Web. It will then show how to efficiently transform a conventional thesaurus into an ontology. At the end there will be time for participants to present problems of knowledge retrieval from their own Web sites, and the group will discuss possible solutions. REFERENCES http:// http:// SALIS2004b.ppt