This volume contains the papers from the technical programmeof the 5th Eu- pean Semantic Web Conference, ESWC 2008, that took place during June 1-5, 2008 in Tenerife, Islas Canarias, Spain. ESWC 2008 was the latest in a series of annual, international events foc- ing on the dissemination and discussion of the latest research and applications of Semantic Web technologies. The call for papers saw over 270 submissions, a comparable ?gure to the previous year, indicating that the conference series has reached a certain level of maturity. The review process was organized - ing a two-tiered system....