The International Planning Competition Series began in 1998 and has been running biennially since that date. The competitions have been an important driver for research in the field. In particular, they have resulted in an evolving language for describing planning domains and problems (PDDL), a body of benchmark domains and problems in that language, and the ability to directly compare different generative planning techniques. All of this has contributed to significant advances in both the character and difficulty of problems that can be represented and solved by generative planning techniques. The papers in this JAIR Special Issue cover the 3rd International Planning Competition (IPC-3), held in conjunction with the 6th International Conference on AI Planning and Scheduling (AIPS-02).