In the two decades since contemporary psychologists produced strong evidence confirming Darwin's century-old hypothesis of the innateness and universality of certain facial expressions of emotions, research on expressive behavior has become well established in developmental, social, and personality psychology and in psychophysiology. There are also signs of increased interest in emotions in clinical psychology and the neurosciences. Despite the success of the work on emotion expression and the upward trend of interest in emotions in general, the fundamental issue of the relation between emotion expression and emotion experience or feeling state remains controversial. A new developmental model of expression-feeling relations provides a framework for reevaluating previous research and for understanding the conditions under which expressions are effective in activating and regulating feeling states. The model has implications for research, socialization practices, and psychotherapy.