The service sector accounts for about two-thirds of the world’s output, it provides more than 50 percent of global employment, and its importance has increased in recent decades in every country (United Nations, 2018). Consequently, millions of service encounters take place every day around the world, with implications for organizations, employees, and customers. Emotions, or intense short-lived feelings associated with an object or target (Ekman, 1994), emerge in service encounters as a main facet that offers valuable insights into the interaction between employees and customers. Due to its complexity, the investigation of emotions in service encounters is carried out from different perspectives. The present chapter emphasizes three aspects. First, although this chapter is not exclusively focused on the display of emotions, I emphasize the outward expression of emotions (Diefendorff & Greguras, 2009) through a combination of facial expression, tone of voice, and spoken words (Rafaeli & Sutton, 1987). Expressed or displayed emotions are not necessarily equivalent to felt emotions. Humans learn to display appropriate emotions in different contexts. Norms, often called display rules, describe the appropriate expressions of emotions in a given social situation (Matsumoto, 1990), including emotions in the service encounter (Diefendorff, Morehart, & Gabriel, 2010; Grandey, Rafaeli, Ravid, Wirtz, & Steiner, 2010). Although expressed and felt emotions might coincide, displayed emotions are the ones that are essential in service encounters because they shape the customers’ evaluations of the social interaction and the service delivery (e.g. Pugh, 2001).