This book constitutes the refereed proceedings of the 8th International Conference on Intelligent Tutoring Systems, ITS 2006, held in Jhongli, Taiwan, June 2006. The book presents 67 revised full papers and 40 poster papers, together with abstracts of 6 keynote talks, organized in topical sections on assessment, authoring tools, bayesian reasoning and decision-theoretic approaches, case-based and analogical reasoning, cognitive models, collaborative learning, e-learning and web-based intelligent tutoring systems, and more.