The SemanticWeb initiative has brought forward the idea that the web may become a space not only for publishing and interlinking documents (through HTML hyperlinks), but also for publishing and interlinking knowledge bases (e.g. in the form of RDF graphs) in an open and fully decentralized environment. This is how Tim Berners-Lee expressed this idea in a note from 1998: The Semantic Web is what we will get if we perform the same globalization process to Knowledge Representation that the Web initially did to Hypertext1 Even though models and languages to achieve this goal have been taken from long-standing research in AI, it is important to remark that the priorities are different. While traditionally the focus has been on theories to support sound and complete reasoning, web-oriented KR primarily aims at dealing with issues of web-wide information interoperability and integration. With respect to this, perhaps the most central issues is Principle of Global Identifiers: ”global naming leads to global network effects” (see Architecture of the World WideWeb, Volume One, 2004, at http://www.w3.org/ TR/2004/REC-webarch-20041215/). In other words, if a resource (where a resource may range from concrete to abstract objects, from particulars to universals) is globally identified through a uniform identifier in any knowledge repository exposed on the web (e.g. in an RDF store), then any knowledge about it would be much easier to gather and integrate, distributed reasoning becomes practically possible, and knowledge-based navigation across interlinked knowledge sources can be enabled. As it happened for the web of documents, the overall value of such an open and distributed network of interlinked knowledge sources would be immensely bigger than the sum of the value of the components. Technically, URIs (Uniform Resource Identifiers, see http://www.w3.org/Addressing/) are used to identify entities on the Semantic Web, but how to achieve shared URI understanding and reuse is object of research. This central role of identity and reference for a web-scale KR poses new challenges to traditional KR, and many researchers have suggested that the concept of URI may deeply affect the notions of language (e.g. the semantics of using the ”same” URI in different models), reference (e.g. rigid vs. non rigid designation), interpretation (e.g. the meaning of ”links” across knowlkedge bases) & reasoning (e.g. distributed reasoning across theories) in traditional logic-based KR in AI. The goal of the workshop on Identity and Reference in web-based Knowledge Representation workshop, which in its past editions was mainly restricted to the Web and Semantic Web communities (see past editions at WWW20062, WWW20073 and ESWC20084), is to open the debate on the impact and the challenges that web-oriented KR poses to some of the core concepts of traditional AI. These working notes collect the papers which have been selected for presentation at the workshop, which was held in conjunction with IJCAI-09 at Pasadena (CA) in July 2009. The papers provide different perspectives on the issue of identity and reference, and are also an illustration of the relevance of the problem and on the diversity of views which exist on it. We’d like to thank all the authors and the participants for their contribution to the success of the workshop.