A key feature of facial behavior is its dynamic quality. However, most previous research has been limited to the use of static images of prototypical expressive patterns. This article explores the role of facial dynamics in the perception of emotions, reviewing relevant empirical evidence demonstrating that dynamic information improves coherence in the identification of affect (particularly for degraded and subtle stimuli), leads to higher emotion judgments (i.e., intensity and arousal), and helps to differentiate between genuine and fake expressions. The findings (...) underline that using static expressions not only poses problems of ecological validity, but also limits our understanding of what facial activity does. Implications for future research on facial activity, particularly for social neuroscience and affective computing, are discussed. (shrink)