Like previous handbooks, the present volume is an authoritative and up-to-date compendium of information and perspective on the neurobiology of ingestive behaviors. It is intended to be stimulating and informative to the practitioner, whether neophyte or senior scholar. It is also intended to be accessible to others who do not investigate the biological bases of food and—fluid ingestion, who may teach aspects of this material or simply wonder about the current state of the field. To all readers, we present this handbook as a progress report, recognizing that the present state of the field is much farther along than it was the last time a handbook was published, but mindful of the likelihood that it is not as far along as it will be when the next handbook is prepared. This field has witnessed a spectacular accretion of scientific information since the first handbook was published in 1967. During the generation of science between then and the publication of the second handbook in 1990, numerous scientific reports have substantially changed the perspective and informational base of the field.