This book is primarily a summary of research done over 10 years in multimedia and virtual reality, which fits within a wider interest of exploiting psychological theory to improve the process of designing interactive systems. The subject matter lies firmly within the field of HCI, with some cross-referencing to software engineering. Extending Sutcliffe's views on the design process to more complex interfaces that have evolved in recent years, this book: *introduces the background to multisensory user interfaces and surveys the design issues and previous HCI research in these areas; *explains the basic psychology for design of multisensory user interfaces, including the Interactive Cognitive Subsystems cognitive model; *describes elaborations of Norman's models of action for multimedia and VR, relates these models to the ICS cognitive model, and explains how the models can be applied to predict the design features necessary for successful interaction; *provides a design process from requirements, user and domain analysis, to design of representation in media or virtual worlds and facilities for user interaction therein; *covers usability evaluation for multisensory interfaces by extending existing well-known HCI approaches of heuristic evaluation and observational usability testing; and *presents two special application areas for multisensory interfaces: educational applications and virtual prototyping for design refinement.