Emotion displays do not only signal emotions but also have social signal value. A study was conducted to test the hypothesis that expressing anger when complaining may lead to positive outcomes for the complainant because anger signals goal obstruction and hence the presence of real harm. The results suggest that the social signal value of anger enhances the credibility of the complainant and hence leads to better compensation, but only when the complaint itself presents room for doubt. For highly justified complaints the additional expression of anger does not add information and is discounted. In contrast, showing an affiliative-smiling demeanor was found to enhance credibility for both types of complaints. Overall, the present research confirmed the important role of emotion expressions as social signals. Copyright # 2008 John Wiley & Sons, Ltd.One of the most pervasive research questions in the psychology of emotions regards the perception of emotion expressions. Most of this research has focused on the decoder's ability to ''get'' the emotional message. In effect, investigations into the decoding process generally stop once an emotion label is affixed to the expression. In contrast, less attention has been devoted to the issue of the inferences that a decoder might draw from that label (Glaser & Salovey, 1998;Hess, Adams, & Kleck, 2008;Manstead, 1991). That is, this line of research often ignores the social implications of showing a certain emotion in a certain context. Emotional expressions do not only express emotions but also have social and communicative functions (e.g., Fridlund, 1991;Fridlund, 1994;Hareli & Rafaeli, 2008;Hess, Kappas, & Banse, 1995;Keltner & Haidt, 1999;Parkinson, 1996;Parkinson, Fischer, & Manstead, 2005), including the signaling of authenticity. Specifically, a communication that includes an emotional signal that matches the meaning of the verbal message will be perceived as more credible than an identical verbal message that does not include such a signal. The goal of the present research was to test this notion in the context of complaints accompanied by anger expressions.The notion that emotional signals interact with verbal content with regard to the perceived credibility of a message is grounded in appraisal theory of emotion. According to appraisal theories of emotion, emotions are elicited and differentiated through a series of appraisals of (internal or external) stimulus events according to the perceived nature of the event. Observers are aware of the ''stories'' that underlie emotions (Parkinson, 1999(Parkinson, , 2001) and hence can ''reverse