process rules in general XML environments as well as special rule engines, to exchange rules between di?erent applications and tools via XSLT translators, as well as to embed rules into other XML content and vice versa. This workshop was dedicated to all aspects of rules and rule markup l- guages for the Semantic Web. RuleML 2004 was the third in a series of wo- shops that was initiated with the International Semantic Web Conference. The previous workshops were held on Sardinia, Italy (2002), and on Sanibel Island, USA (2003). Thisyearwehad25submissions,ofwhich11wereacceptedasregularpapers and another ?ve as short papers describing tools. Wearegratefultoourtwoinvitedspeakers, MikeDeanfromBBNandChr- tine Golbreich from the University of Rennes. Our thanks also go to all subm- ters and reviewers without whom the workshop and these proceedings could not have succeeded.