In Mecanisme de la physionomie humaine, the great nineteenth-century French neurologist Duchenne de Boulogne combined his intimate knowledge of facial anatomy with his skill in photography and expertise in using electricity to stimulate individual facial muscles to produce a fascinating interpretation of the ways in which the human face portrays emotions. This book was pivotal in the development of psychology and physiology as it marked the first time that photography had been used to illustrate, and therefore ‘prove’, a series of experiments. Duchenne’s book, which contained over 100 original photographic prints pasted into the accompanying Album, was rare, even when it first appeared in 1862. Duchenne was a superb clinical neurologist and in this study he applied his enormous experience in neurological research to the question of the mechanism of human facial expression. Duchenne has been little cited and little known in this century; his book has been virtually unobtainable, and copies are available in only a few libraries in the United States and Europe. In this new volume, R. Andrew Cuthbertson has provided the first English translation of Duchenne, complete with a reproduction of the marvellous Album of photographs. The four commentary chapters by modern experts describe the relevance of Duchenne’s findings to the fields of experimental psychology, plastic surgery, neurology, and physiology. This book will therefore be valued by all those who deal with facial expression, including psychologists, physicians, and those involved in the fine arts and photography.