The 3rd International Semantic Web Conference (ISWC 2004) was held November 7–11, 2004 in Hiroshima, Japan. If it is true what the proverb says: “Once by accident, twice by habit, three times by tradition,” then this third ISWC did indeed firmly establish a tradition. After the overwhelming interest in last year’s conference at Sanibel Island, Florida, this year’s conference showed that the Semantic Web is not just a one-day wonder, but has established itself firmly on the research agenda. At a time when special interest meetings with a Semantic Web theme are springing up at major conferences in numerous areas (ACL,
VLDB, ECAI, AAAI, ECML, WWW, to name but a few), the ISWC series has established itself as the primary venue for Semantic Web research.