This book constitutes the refereed post-proceedings of the 12th International Workshop on Design, Specification, and Verification of Interactive Systems, DSV-IS 2005. The 20 revised full papers, 1 keynote paper, and 4 summaries of group discussions are organized in topical sections on teams and groups, sketches and templates, away from the desktop, migration and mobility, analysis tools, model-based design processes and tools, and group discussions.