The gap between formal ontologies and folksonomies is identified, and termed the "Ontology-Folksonomy Divide". This is explored through the application of sociological and psychological models of identity, which are examined and applied to the phenomena of online social networking, using a specially developed analysis framework based on activity theory. Descriptions of roles present in online communities and how they relate to an individualÕs digital identity are explored and a taxonomy of roles is proposed. The methods, technologies, and theory lead to the idea of Folksonomological Reification.