Does a facial expression convey privileged information about a person's mental state or is it a communicative act, divorced from "true" beliefs, desires and intentions? This question is often cast as a dichotomy between competing theoretical perspectives. Theorists like Ekman argue for the primacy of emotion as a determinant of nonverbal behavior: emotions "leak" and only indirectly serve social ends. In contrast, theorists such as Fridlund argue for the primacy of social ends in determining nonverbal displays. This dichotomy has worked to divide virtual character research. Whereas there have been advances in modeling emotion, this work is often seen as irrelevant to the generation of communicative behavior. In this chapter, I review current findings on the interpersonal function of emotion. I"ll discuss recent developments in Social Appraisal theory as a way to bridge this dichotomy and our attempts to model these functions within the context of embodied conversational agents.