THIS study is concerned with the search for a new unity of social knowledge and social inquiry. As such it is addressed to all those who see in the present compartmentalization and special­ ization of the social sciences the reason for the bewildering pro­ liferation of subject matters, the preoccupation with trivia and the failure to make the maximum use of our knowledge for human welfare. More specifically, I am addressing this book to those who are dealing with "interdisciplinary" problems such as the study of foreign areas, the analysis of sociocultural change, economic development of "backward" economies and the planning and teaching of "integrated" courses in the social sciences. The book suggests an answer to the question, How can our specialized knowledge about man and society be unified? As such the study reflects the conviction that all scientific knowledge, in order to make the greatest possible contribution to human welfare, must become comprehensive in character. In fact, such knowledge differs from popular and common-sense understanding precisely by the fact that it is systematically formulated and held together in terms of a few unifying conceptual frameworks. Indeed, all scientific understanding is, above all, an effort to simplify by unifying what has long appeared as unrelated and disparate. Those who believe that compartmentalization and specialization are the royal road to success in the social sciences may find this an irritating book.