This volume reviews recent developments in our understanding of che~ ical signaling in vertebrates. After sections dealing with general princi ples and chemical aspects of vertebrate pheromones, it follows a taxonomic approach, progressing from fish to. mammals. The editors asked a diverse, international group of leading investigators, working on a wide array of vertebrate taxa and specific issues, to consider their efforts from compar ative, evolutionary, and ecological viewpoints. The relative number of manuscripts in each part does not necessarily reflect current intensity of research, since the editors invited speakers who together would provide a balanced and comprehensive overview, while avoiding duplication. Still, the part on mammals is the longest. Fourth in a series dating from 1977, this volume illuminates current trends and likely future developments in the field of chemical signaling in vertebrates. Going back even farther, the first chapter, a personal account of the past quarter century by Dr. Mykytowycz recalls the most important milestones, such as symposia, or the founding of societies and journals. He also credits those investigators who stand out by their seminal studies.