This book constitutes the refereed proceedings of the 11th International Symposium on Methodologies for Intelligent Systems, ISMIS '99, held in Warsaw, Poland, in June 1999. The 66 revised full papers presented together with five invited papers were carefully reviewed and selected from a total of 115 submissions. The volume is divided into topical sections on logics for AI, intelligent information retrieval, intelligent information systems, learning and knowledge discovery, computer vision, knowledge representation, and evolutionary computation.