Contributions to this series aim to integrate social and cognitive development research on the developing child within his/her environment. In the present context, "social" and "cognitive" development are not two separate, nor haphazardly intermingled domains, but are united into one: all cognitive development is social in its nature (as it is guided, although not determined, by the cultural environment), and all social development involves psychological processes that are cognitive in their nature. The approach strives to overcome impasses that are outgrowths of two traditional themes in psychology. First is the fundamental general-biological issue of the contributions of the organism and its environment to the development of the former. The second, almost as pervasive, being how we can understand social development in human ontogeny, and in which ways (if any) human social development differs from that of other species.