When, on April 6, 1917, the Nation was called to war a group of experimental psychologists promptly assembled to consider means of psychological service. As plans of action developed the size of this group, its opportunities and responsibilities, steadily increased. The materials of this report represent the methods and results of only the field of psychological examining. This volume constitutes a complete account of the history, methods, and results of psychological examining in the United States Army. It consists of three parts. Part I is the official history of the development of the service and of its conduct during the war. It is supplemented by reproductions of the printed materials which were devised and used. Part II is devoted to a complete account of the preparation of methods, their characteristics, and their evaluation as practical procedures. In Part III the results of examining are presented in summary fashion. - Summary by Robert M. Yerkes