It is a book about psychology and adult learning as opposed to being a book about the psychology of adult learning. The reader who wants a comprehensive account of psychology and its application to adult learning should look elsewhere. Similarly, the reader who wants an exhaustive treatment of any particular theory will not find it here. My approach has been to examine the seminal traditions of some key psychological theories and to discuss the issues and problems in applying them to an understanding of adult learning and development. I hope it will be useful for those who seek a critical understanding of psychological theory and research from the perspective of the adult educator.