The aim of the CEEMAS conference series is to provide a biennial forum for the presentation of multi-agent research and development results. With its p- ticular geographicalorientation towards Central and Eastern Europe, CEEMAS has become an internationally recognised event with participants from all over the world. After the successful CEEMAS conferences in St. Petersburg (1999), Cracow (2001) and Prague (2003), the 2005 CEEMAS conference takes place in Budapest. The programme committee of the conference series consists of est- lished researchers from the region and renowned international colleagues, sh- ing the prominent rank of CEEMAS among the leading events in multi-agent systems. In the very competitive ?eld of agent oriented conferences and workshops nowadays(suchasAAMAS, WI/IAT, EUMAS, CIA, MATES)thespecialpro?le of CEEMAS is that it is trying to bridge the gap between applied research achievements and theoretical research activities. Our ambition is to provide a forum for presenting theoretical research with an evident application potential, implemented application prototypes and their properties, as well as industrial case studies of successful (but also unsuccessful) agent technology deployments. This is why the CEEMAS proceedings volume provides a collection of research and application papers. The technical research paper section of the proceedings (see pages 11-499) contains pure research papers as well as research results in application settings while the application papers section (see pages 500-530) contains papers focused on application aspects. The goal is to demonstrate the real life value and commercial reality of multi-agent systems as well as to foster communication between academia and industry in this ?eld.