While we have known for centuries that facial expressions can reveal what people are thinking and feeling, it is only recently that the face has been studied scientifically for what it can tell us about internal states, social behavior, and psychopathology. Today's widely available, sophisticated measuring systems have allowed us to conduct a wealth of new research on facial behavior that has contributed enormously to our understanding of the relationship between facial expression and human psychology. The chapters in this volume present the state-of-the-art in this research. They address key topics and questions, such as the dynamic and morphological differences between voluntary and involuntary expressions, the relationship between what people show on their faces and what they say they feel, whether it is possible to use facial behavior to draw distinctions among psychiatric populations, and how far research on automating facial measurement has progressed. The book also includes follow-up commentary on all of the original research presented and a concluding integration and critique of all the contributions made by Paul Ekman. As an essential reference for all those working in the area of facial analysis and expression, this volume will be indispensable for a wide range of professionals and students in the fields of psychology, psychiatry, and behavioral medicine. Paul Ekman was a Professor of Psychology for 32 years in the Department of Psychiatry at the University of California at San Francisco. He also served as chief psychologist in the U.S. Army, Fort Dix New Jersey from 1958-1960. His interests have focused on two separate, but related topics: He originally focused on 'nonverbal' behavior, and by the mid-60s concentrated on the expression and physiology of emotion. His other interest is interpersonal deception. His research program was supported by grants from the National Institute of Mental Health, the National Science Foundation, and the Advanced Research Projects Agency of the DOD, loosely affiliated with UCSF. His many honors have included the Distinguished Scientific Contribution Award of the American Psychological Association in 1991, and an honorary doctor of humane letters from the University of Chicago in 1994. Dr. Ekman retired from UCSF in 2004. He currently serves as the chairman of the board of the Institute of Analytic Interviewing and continues to consult on research and training related to emotion and deception.