Proceedings of the Workshop on Open, Interactive and other Overt Approaches to Learner Modelling, International Conference on Artificial Intelligence in Education (1999 Le Mans, France). The papers in these proceedings are a small but representative sample of the diversity of research in overt learning modelling. Bull and Shurville present an interesting application of interactive learner modelling to the domain of writing, in which the learner (writer) has the initial and final word on the content of the learner model---bearing on the theme of the role of learners in the modelling process. The authors describe an informative study aimed at evaluating whether writers and system can cooperate for the construction of the writer models, the comprehensibility of the models to the writers and the accuracy of their predictions. While all previous research on inspectable learner models has been carried out on the basis of symbolic representations of knowledge, Greer et al. suggest a way in which non-symbolic (Bayesian) learner models can be presented in an attractive and meaningful way to learners. The paper is particularly relevant to the issue of how, and to what extent, complex learner models can be opened to learners' inspection. In the same vein, Morales et al. present a case study showing learner models to learners---in this case, models of sensorimotor skills based on production rules. They raise the issues of modularity of model contents, the modalities in which both the domain tasks and the learner models are presented, and the interactivity of the interface to the models. Dimitrova et al. focus on the interaction between the learner and the learner modelling component of the learning environment. They present a framework for interactive diagnosis in which learner and system talk about the content of the learner model using a graphical language, with the dialogue modelled along the lines of dialogue game theory. Such a framework stretches the possibilities for the role of the learner---and no less importantly, the role of the learner modelling entity---in the modelling process. Brna et al. show how the content of the learner model can be interpreted as an assessment of learners' knowledge, and how it can be constructed in cooperation with the learners. Besides being an application of the concepts of overt learner modelling to assessment, their work provides a nice case in which learner and system would need to assume the roles of negotiants or collaborators, and hence would benefit from a rich model of interaction like the one summarised above. The paper by Vassileva et al. puts overt learning modelling in synchrony with the current trend on structuring intelligent learning environments along the lines of multi-agent systems. The authors suggest a number of ways in which learner models can be used as tools for communication in a hybrid society of human learners and non-human agents interacting in a peer help environment. Their research puts them in an ideal setting for discussing ethical, theoretical and practical issues related to the openness and disclosure of learner models. Finally, Holden and Kay propose to go beyond overt learner modelling by opening to learners' scrutiny other components of tutoring systems and learning environments. Underpinning their approach is the commitment to regard openness as a key element for the design of such systems. In particular, they describe a way of extending the framework provided by the toolkit to make the main user of the learner model---the teaching module---open to learners' inspection and modification.