This book contains a summary of research on the achievement motive conducted mainly at Wesleyan University during the period January 1, 1947, to January 1, 1952, under the continuous moral and financial support of the Office of Naval Research. It provides a practicable method of measuring one of the most important human motives, a method, moreover, which in all probability can be applied to other motives with equal success. Secondly, the book contains what we believe to be an important contribution to psychological theory—at least to the theory of motivation. Finally, the book contains a great deal of information about the achievement motive and related variables.In personality theory there is inevitably a certain impatience—a desire to solve every problem at once so as to get the'whole'personality in focus. The authors have proceeded the other way. By concentrating on one problem, on one motive, they have found in the course of their study that they have learned not only a lot about the achievement motive but other areas of personality as well. So they feel that this book can be used as one basis for evaluating the degree to which a'piecemeal'approach to personality is profitable, an approach which proceeds to build up the total picture out of many small experiments by a slow process of going from fact to hypothesis and back to fact again.