Leading experts critically summarize the state of knowledge concerning the molecular, anatomical, physiological, and behavioral aspects of NPY and its congeners. Each article provides a comprehensive and in-depth survey, an overview of the role of NPY in the discipline covered, a discussion of the likely future direction that the field will take, and an up-to-date bibliography. Chapters include a treatment of the evolution of the PP family of genes, the structure of the NPY gene, and the distribution of NPY on the cardiovascular system, actions of NPY on the electrophysiological properties of nerve cells, and the effects of NPY on feeding and behavior. The chapters are written in an accessible style and serve both as an introduction to the field and as an extensive and detailed treatment of the current state of knowledge.