This study appears at a time when a decisive turn is due in the research on personality development. After many years of stagna tion and misguided research in this field, this book should lead to a thorough revision and a better understanding of current views on the factors which have an influence on personality. Let us consider the unsatisfactory aspects of the recent develop ments in personality studies. At the beginning of this century, the revolutionary insight gained ground that personality is susceptible to various influences, in particular to those resulting from human interaction. This insight swept away many of the old scholastic concepts and gained special importance in the fields of pedagogics and psychotherapy. How ever, in the wake of every great discovery we find inherent dangers. For years, various claims and creeds on the malleability of personality have been put forward as if they were proven facts. Lay literature, too, was permeated with wrong and distorted information on factors which might endanger child development.