This book derives from a workshop entitled 'Natural Dialogue and Interactive Stu dent Modeling', held October 17-20, 1992 in the Villa Cipressi in Varenna (Italy). The theme of the workshop focused on how approaches to natural dialogue and conversation contributed to the development ofa sophisticated dialogue component in intelligent tutoring systems. Researchers from the fields of educational technol ogy, dialogue research and user interface design were all invited to the workshop in order to ensure a broad knowledge base for the discussion of the main topic of the workshop. The workshop included a variety of presentations, most of which are presented in this book, as well as active discussions of a number of issues related to the main topic, such as: the intrinsic value of a dialogue component in an intelligent tutoring system verbal expressions (e.g., natural language) as a successful modality in a learning setting the application of results from other types of dialogue, such as information or task dialogues, in models of instructional dialogue the role of a teacher as an intermediary who provides motivation and support in learning as opposed to the role of a teacher as someone who just presents information. In the introductory chapter we have tried to combine these issues and link them to the papers that are presented in this volume.