Originally published in 1985, the aim of this book was to examine the development of adaptive skills in a comparative context. Comparative explorations have evolutionary implications. Thus it is inevitable that the contributors to this volume, all of whom come to the study of development with a comparative perspective, manifest concern with the relationships between ontogeny and phylogeny. In this volume both field and laboratory approaches are presented. It is quite clear that the laboratory studies are increasingly informed by ecological considerations that derive from field excursions. It is also the case that laboratory findings are becoming an essential source in directing field inquiries. The problems explored are theoretically rich and methodically significant and the comparative scope of the contributions range widely among vertebrate species.