This collection of thoroughly refereed papers presents state-of-the-art research results by well-known researchers on the foundations of knowledge representation and reasoning. In addition, there are two surveys, one by the volume editors intended as a guide to this book and another by Shoham and Cousins on mental attitudes. In total, the volume provides a well-organized report on current research in knowledge representation, which is one of the central subfields of AI. Except the surveys, the papers grew out of a workshop on Theoretical Foundations of Knowledge Representation and Reasoning, held in conjunction with the 10th European Conference on Artificial Intelligence (ECAI-92) in Vienna in August 1992.