This book is an elaboration of the author's previous Mental Hygiene and Education (1934). Its purpose is to give the background material for courses in mental hygiene by 'presenting the clinical, experimental, psychological, and psychiatric data of a number of basic problems of behavior'. It promises further to present and evaluate current theories. Since the book includes emotions, motivation and frustration, personality adjustment, attitudes, conflicts, delinquent behavior, the neuroses, and mental abnormalities, this is a big order indeed.