Since the first drawings left on walls of ancient caves, human beings have been fascinated with that unique phenomenon of the animal kingdom, the presence of horns and antlers. From the mythical ''unicorn'' exercising the power over life and death to the perceived aphrodisiacal and other medical properties of rhinoceros horns and growing antlers, these conspicuous protuberances have had a significant place in the history of mankind. Part of that ancient interest in antlers and horns was due to their value as sym- bols of masculinity; this interest persists today in trophy hunting, an honorable tradition carried on for centuries in many countries of the world. This book, which deals with evolution, morphology, physiology, and behavior, has not been devised as a comprehensive review of the subject of horns, prong- horns, and antlers; rather, it is a series of chapters stimulating thoughts, discus- sions, and initiation of new studies. As editors, we did not interfere with the content of articles nor with the opin- ions and interpretations of our contributors, and we left them to decide whether to accept the suggestions of our reviewers. Despite the fact that various aspects of cranial appendages have been studied since the end of the eighteenth century, many controversial views still exist, as witnessed in various chapters of this book.