The aim of IFIP Working Group 2.7 (13.4) for User Interface Engineering is to investigate the nature, concepts and construction of user interfaces for software systems. The group's scope is: * developing user interfaces based on knowledge of system and user behaviour; * developing frameworks for reasoning about interactive systems; and * developing engineering models for user interfaces. Every three years, the group holds a "working conference" on these issues. The conference mixes elements of a regular conference and a workshop. As in a regular conference, the papers describe relatively mature work and are thoroughly reviewed. As in a workshop, the audience is kept small, to enable in-depth discussions. The conference is held over 5-days (instead of the usual 3-days) to allow such discussions. Each paper is discussed after it is presented. A transcript of the discussion is found at the end of each paper in these proceedings, giving important insights about the paper. Each session was assigned a "notes taker", whose responsibility was to collect/transcribe the questions and answers during the session. After the conference, the original transcripts were distributed (via the Web) to the attendees and modifications that clarified the discussions were accepted.