This book is about the two-way interplay between vision and action. Vision acts to guide and control actions. But vision also obtains a lot of information about the world by virtue of these actions - for example by moving round an object to obtain successive views. This becomes a reiterative process and it is this that is the focus of this volume. This book contains contributions from scientists who are leaders in each of the several facets of the subject. Examples of the types of action considered vary from moving the eyes and head and body, as in looking around or walking, to complex actions such as driving a car, or playing table tennis.