This book constitutes the refereed proceedings of the Fourth International Conference on Intelligent Tutoring Systems, ITS'98, held in San Antonio, Texas, USA, in August 1998. The 60 revised full papers presented were carefully reviewed and selected for inclusion in the proceedings. The book is organized in topical sections on architectures for ITS, design and interface issues, tutoring and authoring tools, collaborative learning, knowledge structure and representation, teaching and learning strategies, applications of ITS, student modeling, educational agents, deploying ITS, and Web-based ITS.