"Who stays well?" should be the central question in health care today, according to Friedman, a Univ. of California professor of psychology and community medicine. To answer that question, he analyzes the self-healing personality and its opposite, the disease-prone personality. Friedman sees three links between personality and health: genetic temperament, physiological response to stress, and behavior. He concentrates on the second, noting that under stress some individuals are much better than others at maintaining an internal equilibrium. Achieving internal balance, he says, will not only help prevent disease but also slow or halt the progression of chronic disease. To describe emotional patterns of imbalance, he draws on the ancient Greek humors--the melancholic or depressed, the phlegmatic or apathetic, and the choleric or hostile. The balanced personality he terms "sanguine" or "enthusiastic." To the extent that individuals can move from a pattern of imbalance to one of balance, the healthier they will become. Friedman discusses techniques for doing this and identifies the most appropriate for each type--e.g., systematic relaxation works well for cholerics but not for phlegmatics. He also identifies techniques that simply do not work, e.g., color therapy and subliminal suggestion tapes. Finally, Friedman calls for changes in today's healthcare system, which focuses on treatment of diseases rather than promotion of health and which overemphasizes the biological factors involved in illness while underestimating the importance of psychosocial ones. Not a simple how-to book for transforming one's personality, but a cogent argument for paying greater attention to the psychological and social aspects of wellness and illness.