This book is a continuation and elaboration of the studies of infancy reported in a previous publication in 1934, Infant Behavior, its Genesis and Growth. It combines the features of a monograph and handbook. Dr. Gesell states its purpose to be to furnish definite methods of behaviour examination in infants, and to provide norms of certain aspects of developmental behaviour which can be used in the analytic appraisal of behaviour for purposes of genetic research or for clinical diagnosis.

One hundred and seven infants were studied and reported on and 524 examinations were made. Twenty-four of these babies (12 boys and 12 girls) were examined consecutively at fifteen age levels, four to fifty-six months, to determine 'growth of behaviour'.

Part One describes in detail methods of selecting a homogeneous