This volume presents recent progress in our understanding of various mechanisms involved in chemical communication between individual animals. Such communication is important for survival and reproduction of any vertebrate species in a variable environment. Apart from visual and acoustic signals, many animals developed highly complex means of conveying message by odor and taste. Low molecular weight and volatile compounds known as pheromones affect many metabolic processes and behavioral traits. The chapters in this volume are derived from presentations and discussions at the Ninth International Symposium on Chemical Signals in Vertebrates, held at the Jagiellonian University, Krakow, Poland, on July 25-29, 2000. The four days and nights of discussions at the conference explored diverse topics in chemical communication, and many of the chapters in this volume were improved by revisions in which the authors took into account the discussions in Krakow.