In the five years since the publication of the First Edition, a tremendous amount of research has been conducted attempting to relate macromolecules and behavior. New approaches to the overall problem have developed. Several chapters of the First Edition were not continued in this edition; most of those which were included have been revised thoroughly. A number of chapters by other contributors were invited to help round out the volume. New chapters are those by Glassman and Wilson; Squire and Barondes; Ungar; Jankovic; Hyden and Lange; Koenig; Appel; Rosenzweig, Bennett, and Diamond; and Deutsch. This edition should provide a representative view of the important research and theorizing which is occurring in this area. This volume is built around two important topics: Products of DNA Activa- tion (Section II) and Macromolecules and Intracellular, Intercellular, and Synaptic Events (Section III). The Introduction (Section I) leads to these topics, and Models of Memory (Section IV) attempts to provide an integration of these topics with brain function. The preparation of this volume was facilitated by grants from the National Research Council (Canada) and by Contract No. Nom 4935(00) with the Physiological Psychology Division of the Office of Naval Research (U .S.A.) .