Facet is an established methodology for building classifications and subject indexing systems, but has been less rigorously applied to thesauri. The process of creating a compatible thesaurus from the schedules of the Bliss Bibliographic Classification 2nd edition highlights the ways in which the conceptual relationships in a subject field are handled in the two types of retrieval languages. An underlying uniformity of theory is established, and the way in which software can manage the relationships is discussed. The manner of displaying verbal expressions of concepts (vocabulary control) is also considered, but is found to be less well controlled in the classification than in the thesaurus. Nevertheless, there is good reason to think that facet analysis provides a sound basis for structuring a variety of knowledge organization tools.