Abstract
This paper explores the concept of a work in WorldCat, the OCLC Online Union Catalog, using the hierarchy of bibliographic entities defined in the Functional Requirements for Bibliographic Records (FRBR) report. A methodology is described for constructing a sample of works by applying the FRBR model to randomly selected WorldCat records. This sample is used to estimate the number of works in WorldCat, and describe some of their key characteristics. Results suggest that the majority of benefits associated with applying FRBR to WorldCat could be obtained by concentrating on a relatively small number of complex works.