This book constitutes the ninth official archival publication devoted to RoboCup, documenting presentations at the RoboCup 2005 International Symposium, held in Osaka, Japan, July 2005 alongside the RoboCup Competition. The book presents 34 revised full papers and 38 revised short papers together with two award-winning papers. This is a valuable source of reference and inspiration for those interested in robotics or distributed intelligence, and mandatory reading for the rapidly growing RoboCup community.