The 21 revised full papers and 10 late breaking and experience report papers presented were carefully reviewed and selected from numerous submissions for inclusion in the book. The papers cover user interface evaluation and specification, with particular emphasis on the use of task models to provide high-level approaches for capturing the intended functionality of a user interface; examining techniques for modeling user interfaces, particularly for mobile and ubiquitous applications; advanced implementation techniques for interactive systems; and architecture of interactive systems with special focus on evaluation and specification.