The primary purpose of this book is to trace the theoretical methodological foundations of American educational technology. It must be emphasized that this work is essentially as history of the process of educational technology rather than of products in the form of devices or media. Although media have played an important rode in educational technology, the reader should not lose sight of the central process which characterizes and underlies the true historical meaning and function of educational technology. Moreover, the assumption is made that all current theory, methodology, and practice rests upon the heritage of the past. Indeed, a common problem in the field has been the failure, in many instances, to take adequate account of past history in planning for the present or the future. A related purpose of this book is to provide a selective survey of research in educational technology as it relates to the American public schools. Such research reviews are not intended to be comprehensive, but were included because of their historical importance and their relevance in understanding the process of educational technology.