The Daniel S. Lehrman Memorial Symposia Series will publish the proceedings of symposia devoted to the evolution, development, and organization of behavior. These various symposia will bring together at intervals scientists studying problems from each of these view­ points. The aim is to attempt to integrate our knowledge derived from these different sources and to familiarize scientists working on similar behavior patterns with the work of their colleagues in related fields of study. Each volume, therefore, will be devoted to a specific topic in the field of animal behavior, which will be explored with respect to its evolutionary aspects, including the adaptive nature of the behav­ ior; with respect to its developmental aspects, including neural, hor­ monal, and experiential influences; and with respect to the analysis of features of organization, including motivational, perceptual, and motor aspects and their physiological bases. It is our feeling that the most appropriate memorial to our colleague and close friend, Daniel S. Lehrman, is the continuation of his valuable contributions toward integrating these approaches to the study of animal behavior, which he pursued so effectively during his own life. Daniel S. Lehrman's lifelong love and study of animal behavior gave us a wealth of new insights into reproductive behavior and evolution. It is therefore appropriate that the first symposium of this series is devoted to recent advances in this field.