This book constitutes the refereed proceedings of the Third Mexican International Conference on Artificial Intelligence, MICAI 2004, held in Mexico City, Mexico in April 2004. The 94 revised full papers presented were carefully reviewed and selected from 254 submissions. The papers are organized in topical sections on applications, intelligent interfaces and speech processing, knowledge representation, logic and constraint programming, machine learning and data mining, multiagent systems and distributed AI, natural language processing, uncertainty reasoning, vision, evolutionary computation, modeling and intelligent control, neural networks, and robotics.