Abstract This paper presents a discussion of crowdsourcing approaches to knowledge organization and more specifically to the development of classification schemes. It analyzes the case of Open Shelves Classification, a terminated project that was developed by the LibraryThing community following the “open source model”, and assesses its outcomes from methodological and sociological points of view. Working with all the documentation of the project that is freely available, the text conducts an analysis of the project following the structure of the methodological lessons for open source (Bazaar model) presented by Eric Raymond in his seminal work “The Cathedral and the Bazaar” and complementing it with the discussion of the sociological aspects presented in “Homesteading the Noosphere” and other writings. The paper concludes with some recommendations for the success of open source projects and some possibilities of research for crowdsourcing projects and social epistemology.