The DARPA Urban Challenge required robots to drive 60 miles on suburban roads while following the rules of the road in interactions with human drivers and other robots. Tartan Racing’s Boss won the competition, completing the course in just over 4 hours. This paper describes the software infrastructure developed by the team to support the perception, planning, behavior generation, and other artificial intelligence components of Boss. We discuss the organizing principles of the infrastructure, as well as details of the operator interface, interprocess communications, data logging, system configuration, process management, and task framework, with attention to the requirements that led to the design. We identify the requirements as valuable re-usable artifacts of the development process.