An in-depth study of faceted classification theory, as presented by Ranganathan and further developed by Brian Vickery and the Classification Research Group, led to the creation of a methodology based on the Postulate of Fundamental Categories, the Postulate of Basic Facet and the Postulate of Isolate Facet. This methodology was then used to analyze the facets of a dataset consisting of over 107,000 instances of 1,275 unique tags representing 76 popular non-fiction history books collected from the LibraryThing folksonomy (see http://www.librarything.com/). Preliminary results of the facet analysis show the manually-produced, two-faceted classification models in the dataset, one representing the universe of books, and the other representing the universe of subjects within the universe of books. The model representing the universe of books is considered to be complete, whereas the model representing the universe of books is then compared to other models of books, including the BIBO ontology and the FRBR model. Finally, the models are discussed in terms of their confirmation or violation of Ranganathan’s seven Canons of Classification, upon which the postulates are based.