This book constitutes the refereed proceedings of the 25th Annual German conference on Artificial Intelligence, KI 2002, held in Aachen, Germany in September 2002. The 20 revised full papers presented were carefully reviewed and selected from 58 submissions. The book offers topical sections on natural language processing; machine learning; knowledge representation, semantic web, and AI; neural networks; logic programming, theorem proving, and model checking; and vision and spatial reasoning.