Book excerpt: Does modelling, formal or otherwise, play a role in designing interactive systems? A proliferation of interactive devices and technologies is used in an ever increasing diversity of contexts and combinations in professional and every-day life. This development poses a significant challenge to modelling approaches used for the design of interactive systems. The papers in this volume discuss a range of modelling approaches, the representations they use, the strengths and weaknesses of their associated specification and analysis techniques and their role in supporting the design of interactive systems.