THE PRESENT CRISIS in world affairs has resulted in a flood of books. Most of these are concerned with plans for world reorganization. The purpose of the present volume is much less ambitious. Everyone recognizes that such planning will require all the aid which science can give. At the same time, the problems involved are complex and many sided and can only be solved by collaboration between workers in many different fields of scientific research. It has been observed that it usually takes about a generation for the new discoveries and techniques of one science to become a part of the regular working equipment of other sciences. It takes considerably longer for such findings to become familiar to the layman and to exert any significant influence upon his thinking. The present book is an attempt to shorten this time interval. It is directed both to scientists and planners and to the general public without whose cooperation no plan can succeed. The science of man is so new and its fund of knowledge has been increasing so rapidly that many of its findings have not yet reached scientific workers in other fields, let alone the man in the street. At the same time, some of these findings are of the utmost importance both for the intelligent planning of the new world order which now appears inevitable and for the implementation of any plans which may be made. The builders of such an order are foredoomed to failure unless they understand the potentialities and limitations of their human material. Scarcely less important is a knowledge of those trends which operate over long periods of time and of the problems which the specialist can foresee before they arise or can recognize before they become acute enough to call for drastic action. Lastly, even plans which take all these factors into account cannot succeed without the use of adequate techniques. At all these points the science of man can provide some aid. In the preparation of the present volume the editor has been confronted with certain wartime limitations with regard to both space and personnel. A very large proportion of the younger scientists in this field are engaged in government service, many of them with the armed forces. After due consideration it was decided to make this book a report from the frontiers of research, the outposts of science rather than its settled hinterland. This has resulted in the exclusion of various subjects which might well have been included under other circumstances. Facts which are all ready well known have been passed over lightly and various problems which are already widely recognized and discussed have been omitted. Thus it has been taken for granted that the average reader knows and accepts the basic facts of man"s origin and evolution and no space has been devoted to them. However," since much of our most recent knowledge of race has not reached the layman, this has been dealt with at some length. Again, the problems of Jewish and Negro minorities have not been dealt with specifically. Everyone is conscious of the existence of these problems and the literature dealing with them is already voluminous. They have been passed over in favor of a presentation of our new knowledge regarding the problems of minority groups in general. On the other hand, the looming problem of how to deal with the American Indian has been given considerable space since most laymen scarcely realize that such a problem exists. While such selectivity is sure to arouse criticism in certain quarters it is hoped that the present book will be judged on the basis of what it includes, not what it omits.