This book is about play behaviour: what it is, what it is for, how we decribe and study it and how it evolved. The last ten years or so have seen a great burgeoning of interest in these questions among both psychologists and zoologists. This book draws together work on both animals and children to show what has been achieved. It illustrates how much of this research coheres around the theme of development: play seen from the perspective of the evolutionary development of a species and play seen as crucial aspect of individual development. Combining general theoretical accounts of play behaviour with detailed discussion of research on particular species (including kittens, monkeys and rodents), Peter K. Smith sets out to relate this work on animal behaviour to psychological research on human play among young children, those of school age and adults. The topics covered include fantasy play, imaginary companions, object play, problem solving, rough and tumble play and children's games.