This book is the fourth offical archival publication devoted to RoboCup and documents the achievements presented at the Fourth Robot World Cup Soccer Games and Conferences, RoboCup 2000, held in Melbourne, Australia, in August/September 2000. The book presents the following parts: introductory overview and survey, championship papers by the winners of the competitions, finalist papers for the RoboCup challenge awards, papers and posters presented at the workshop, team description of a large number of participating teams. This book is mandatory reading for the rapidly growing RoboCup community as well as a valuable source of reference and inspiration for R & D professionals interested in multi-agent systems, distributed artificial intelligence, and intelligent robotics.