Unlike most texts that are the work of a number of contributors, this volume by twelve representative American psychologists has an unusual consistency of approach. It is a thorough survey of the animal field from the behaviorist and experimental point of view, well documented and for the most part well written. Particularly outstanding are the chapters on Theories of Learning (by E. C. Tolman) and The Conditioned Reflex (by H. S. Lidell); the latter is the most succinct and generally most accurate exposition of the subject that the reviewer has as yet come across. The content