This is a book about the development of action and skill in the first years of life. But it differs in an important way from most past treatments of the subject. The present volume explores how the development of ac tion is related to the contexts, especially the social ones, in which actions function. In past work, little attention has focused on this relationship. The prevailing view has been that infants develop skills on their own, independent of contributions from other individuals or the surrounding culture. The present volume is a challenge to that view. It is based on the premise that many early skills are embedded in interpersonal activities or are influenced by the activities of other individuals. It assumes further that by examining how skills function in interpersonal contexts, insights will be gained into their acquisition and structuring. In effect, this vol ume suggests that the development of cognitive, perceptual, and motor skills needs to be reexamined in relation to the goals and contexts that are inherently associated with these skills. The contributors to the vol ume have all adopted this general perspective. They seek to understand the development of early action by considering the functioning of action in context. Our motivation for addressing these issues stemmed in part from a growing sense of dissatisfaction as we surveyed the literature on skill development in early childhood.