This book constitutes the refereed proceedings of the 20th International Conference on Industrial and Engineering Applications of Artificial Intelligence and Expert Systems, IEA/AIE 2007, held in Kyoto, Japan in June 2007.The 116 revised full papers presented together with 2 invited contributions were carefully reviewed and selected from 462 submissions. The papers are organized in topical sections on text processing, fuzzy system applications, vision, real-world interaction, genetic algorithm robotics, fuzzy logic, manufacturing, data mining, neural network, constraint satisfaction, machine learning chance discovery and social network, education, speech, e-commerce, heuristic search application system, agent-based system, and other applications.