Since this volume is designed to promote this change of practice, it is fitting that it should Open with a brief inquiry into the causes of the anomalous state of affairs at present Obtaining and with some indication of the way in which it is hoped that the change may be brought about. For there can be no question that the lack Of practical recognition of psychology by the workers in the social sciences has been in the main due to its deficiencies, and that the only way of establishing it in its true place is to make good these deficiencies. What, then, are these deficiencies, and why have they so long persisted? We may attempt very brie?y to indicate the answers to these questions without presuming to apportion any blame for the long continuance Of these deficiencies between the professed psychologists and the workers in the social.