Robotic soccer superseded chess as a challenge problem and benchmark for artificial intelligence research and poses many challenges for robotics. The international RoboCup championships grew to the most important robotic competition worldwide. This paper describes the mechanical and electrical design of the robots that we constructed for RoboCup 2006, which took place in Bremen, Germany. The paper also covers the software used for perception, behavior control, communication, and simulation. Our robots performed well. The KidSize robots won the Penalty Kick competition and came in second the overall Best Humanoid ranking, next only to the titleholder, Team Osaka.