In the early 1980s the transtheoretical model of change was still in its infancy. Seminal publications were just appearing, but the model already seemed to hold such promise that we made it the organizing theme for the Third International Conference on Treatment of Addictive Behaviors (ICTAB-3), which convened in Scotland in 1984. That meeting gave rise to the first edition of this volume (Miller & Heather, 1986), which focused on processes involved in moving people from one stage to the next. With the volume still in print more than a decade later, we were approached by Plenum Press with the idea of preparing this second edition. We were, obvi­ ously, persuaded that there was merit to the idea. Since 1986 the work of Pro­ chaska and DiClemente has grown exponentially in popularity and influence. In Britain and the Americas, it is now unusual to find an addiction professional who has not at least heard about the stages of change, and more sophisticated applications of the transtheoretical model are spreading through health care systems and well beyond. The model has influenced professional training, health care delivery, and the design of many studies including a number of large clinical trials.