Since this book first appeared in 1934, sociometry has been through many stages in rapid development. It has been identified not only with the rigorous application of research techniques to specific problems in human behavior; it has also grown along the lines of social healing, diagnosis and therapy. Simultaneously, sociometry has come forth with a theory of human behavior-on one hand, as a system of propositions rather solidly grounded in research findings, and on the other hand through its speculative considerations, it has aimed at capturing the imaginative mind. It is fair to say that the all-important foundations of sociometry have, by now, been built. This basis is one which consists of thousands and thousands of investigations, generally limited to various types of groups and small communities.