This book is the product of many years' experience teaching behavioral science in a way that demonstrates its relevance to clinical medicine. We have been guided by the reactions and evaluations of many first-year medical students. The result is a conceptual framework different from those that we and others had tried before. Because the clinical relevance of knowledge about human behavior is less apparent to many first-year students than that of the other traditional pre- clinical courses, books and courses organized as brief introductions to psychology, sociology, and behavioral neurology have often been poorly received. Various medical schools and texts have explored ways to overcome this difficulty. One text organizes the presentation around very practical problems which are of unmistakable interest to the future physician: the therapeutic relationship, death and dying, sexuality, and pain, to give a few examples. Another emphasizes stages of development, periods of the human life cycle, as its organizing principle. Both of these approaches have merit and have been used successfully in various schools. They seem to us, however, to have a potentially serious shortcoming. They focus student attention too much on the more immediately intriguing issues of specific clinical problems or on the more easily recognized age- specific behavioral issues. In the limited time available, the teaching of general principles of human behavioral functioning may then be neglected.