This volume contains the papers presented at the 2nd European Semantic Web Conference (ESWC 2005) held in Heraklion, Crete, Greece, from 29th May to 1st June, 2005. The vision of the Semantic Web is to enhance today’s Web via the exploi- tion of machine-processable metadata. The explicit representation of the sem- tics of data, accompanied with domain theories (ontologies), will enable a web that provides a qualitatively new level of service. It will weave together an - crediblylargenetworkofhumanknowledgeandwillcomplementitwithmachine processability. Various automated services will help the user to achieve goals by accessing and providing information in a machine-understandable form. This process may ultimately create extremely knowledgeable systems with various specialized reasoning services systems. Many technologies and methodologies are being developed within arti?cial intelligence, human language technology, machine learning, databases, software engineering and information systems that can contribute to the realization of this vision. The 2nd Annual European Semantic Web Conference presented the latest results in research and applications of Semantic Web technologies. Following the success of the ?rst edition, ESWC showed a signi?cant increase in participation. With148submissions,thenumberofpapersdoubledthatofthepreviousedition. Each submission was evaluated by at least three reviewers. The selection process resulted in the acceptance of 48 papers for publication and presentation at the conference (an acceptance rate of 32%). Papers did not come only from Europe but also from other continents.