Although it has been assumed since early recorded history that psycho logical factors influence health and illness, it has only been within the past few years that a group of investigators and clinicians with a shared interest in the application of psychological principles and techniques to health and illness has existed. Over this same period of time, a number of multi-author books on the topic of health psychology and an associ ated field, behavioral medicine, have been published. Although these books are major resources for the investigator and the clinician in the field, it is often difficult for students, both undergraduate and graduate, to learn the basics of health psychology from such books. Thus, Health Psychology: A Psychobiological Perspective was written to provide such basics. The need for such a textbook in health psychology became appar ent to the first author when he was searching for reading material for an undergraduate course in health psychology at McGill University. This book grew out of the course in health psychology, and its structure represents the course content. The purpose of the book is to present the theoretical, empirical, and clinical aspects of the rapidly developing field of health psychology. Data from a number of subdisciplines within psychology and the behav ioral and health-related sciences are integrated throughout each chapter in an effort to provide a balanced perspective. Health Psychology explores the development of the field and its research methodologies, theoretical models, and intervention possibilities.