This book is an effort to integrate some clinical observations, theoretical concepts, and promising clinical procedures that relate psychological variables to physiological variables. My primary emphasis is on what psychological and behavioral concepts and procedures are most likely to enable us to influence physiological functions. The book covers ques tions that have fascinated me and with which I have struggled in daily clinical practice. What types of people are most at risk for physical disor ders or dysfunctions? Why do some people present psychosocial con flicts somatically and others behaviorally? What is the placebo effect and how does it work? How do you arrange the conditions to alter maladap tive belief systems that contribute to psychopathology and patho physiology? Do beliefs have biological consequences? When I was in private clinical practice, and even today in my medi cal school clinical practice situation, I set aside one day each week to puzzle over the theoretical questions that my clinical experience gener ates. Often isolating these underlying theoretical questions provides guidance into the most relevant empirical literature. I have found that this weekly ritual, which I started in private practice many years ago, appears to increase my clinical efficacy or at least makes clinical work more exciting. I find the unexamined clinical practice hard to endure. Kurt Lewin once said, There is nothing so practical as a good theory.