From Theory to Design. The importance of models in making complex systems comprehensible (G. Fischer). Methodological Aspects. Models of mental models: an ergonomist-psychologist dialogue (A. Rutherford and J.R. Wilson). How to t(r)ap user's mental models (M.–A. Sasse). Modelling for adaptivity (D. Murray). Concurrent use of different expertise elicitation methods applied to the study of the programming activity (W. Visser and A. Morais). Analysing complex tasks with an extended GOMS* model (U. Arend). Object-based action planning (J. Beringer and J. Wandmacher). Empirical Results. Design decisions for a user interface (F.M.T. Brazier and G.C. van der Veer). Mental models and the evaluation of user interfaces: a case-study of a library system (J.M. van der Velden and A.G. Arnold). Level of experience in text-editing: the role of mental representations on performance (A. Dewier and G. Karnas). How to predict user performance and user preference with different interaction techniques? (Ch. Metzler, E. Wetzenstein-Ollenschläger and H. Wandke). A schema-based model of program-understanding (F. Détienne). Mental Models in Design. Cognitive processes in information retrieval: production rules and lexical nets (M. Wettler and A. Glöckner-Rist). Modelling the user interaction methods imposed by design (J. Karat and J. Bennett). Usability testing: a practical use for mental model construction (P.R. Innocent). Mental Models and Artificial Intelligence. Plan recognition in HCI: the parsing of user actions (M.C. Desmarais, L. Giroux and S. Larochelle). Inductive knowledge acquisition for a UNIX coach (H.U. Hoppe and R. Plötzner). The psychological processes of constructing a mental model when learning by being told, from examples, and by exploration (F. Schmalhofer and O. Kühn). Domain Representation and student modelling in a microworld for elastic impacts (K.