This book is divided into Sections. Each Section is devoted to a particular theme in Motor Development and comprises two or more contributions. The order of presentation is largely fortuitous and does not reflect any value judgement on the part of the editors as to the importance of anyone theme in comparison to others addressed' in the book. This volume is to be seen as a companion volume to 'Motor Development in Children: Aspects of coordination and control' in which the more general issues in motor development presented during the Institute are published. Together, the two volumes provide both a general and a theme specific approach to this expanding field of knowledge. XI PREFACE Books and conferences, on what in North America is euphemistically termed motor development, have been few and far between in the past 25 years. This is not to say that the study of how children acquire and develop motor skills has not been a subject on which scientists have focused their attention. In the United States in the 1930's and 1940's, Bayley (1935) and Gesell and Amatruda (1947) described and scaled the rates at which young children acquired motor skills. In Europe, the development of childrens' motor behaviour was of theoretical interest to Piaget (1952).