Information seeking activities, whether in databases, knowledge bases, or any kind of information system are highly interactive processes. User interfaces to information systems should enable the end user, to retrieve the data without help from an intermediary expert. Knowledge about information seeking tasks and strategies of the user, as well as the related system’s functionality are starting points to build up cases of information seeking dialogues and to adapt cases to a new information need. We use a case for two purposes: first, for controlling the interaction, that means going forward and backward in the dialogue plan or history, and second, as a means to guide the user through the information space and through the interaction with the system. In contrast to most domains of case-based reasoners, our domain is underconstrained and highly interactive. Therefore, the adaptation of cases can be done only with mixed initiative of user and system. Our approach is implemented in a prototype of a case-based dialogue manager (CADI), applied in the MERIT interface system to the CORDIS databases. Currently, we are implemting CAIRO (Case-Based Dialogues for Information Retrieval Objectives), a further interface system to CORDIS dtaa, now focusing on case-based user guidance according to information seeking strategies.