Darwin's work of 1872 still provides the point of departure for research in the theory of emotion and expression. Although he lacked the modern research tool of cybernetics, his basic methods have not been improved upon: the study of infants, of the insane, of paintings and sculpture, of some of the commoner animals; the use of photographs of expression submitted to different judges; and the comparative study of expression among different peoples. This new edition will be warmly welcomed by those behavioral scientists who have recently shown an intense interest in the scientific study of expression. Lay readers, too, will be struck by the freshness and directness of this book, which includes, among other data, Darwin's delightfully objective analysis of his own baby's smiles and pouts.