Adaptive Hypermedia and Adaptive Web Based Systems : Third International Conference AH 2004 Eindhoven The Netherlands August 23 26 2004. Proceedings This book constitutes the refereed proceedings of the Third International Conference on Adaptive Hypermedia and Adaptive Web Based Systems AH 2004 held in Eindhoven The Netherlands in August 2004. The 27 revised full papers and 18 revised short papers presented together with 3 abstracts of keynote talks 4 doctoral consortium presentations and 17 posters were carefully reviewed and selected from 138 submissions. The papers provide an excellent view on innovative personalization and adaptation functionalities in a variety of areas including e learning e commerce mobile tourist guides etc; they also show the integration of personalization functionalities employed in Web environments in ambient intelligence and intelligent agents contexts and building upon adaptive hypermedia and semantic Web technologies Web search Web services social and peer to peer networks and recommender systems