The broaden-and-build theory of positive emotion suggests that positive emotions should broaden thought and behavior repertoires in order to develop lasting resources. In the social domain, this means deploying a variety of affiliative strategies in order to build cooperative relationships. A functionalist perspective on positive emotion suggests that different positive emotions should have distinct effects on these affiliative mechanisms. This study elicited awe, amusement, pride or a neutral control in pairs of same sex strangers. They then completed an open-ended "getting to know you" conversation, which were recorded and coded for affiliative behaviors—smiling, laughter, mimicry, and asking questions. After, they rated their perception of the other as complex and how much they liked each other. Then they played the prisoner's dilemma game. Results indicate that there was a significant mediated effect such that being in the pride condition predicted greater smiling, and smiling predicted cooperation on the prisoner's dilemma. This was true both when an individual's own smiling was predicting their cooperative behavior and when their partner's smiling was predicting their cooperative behavior. However, these effects were only seen in female dyads, not male dyads. There was also a significant mediated effect such that pride led women to ask more questions, which led partners to like each other more. Additionally, awe led to greater mimicry in men, which in turn led to greater cooperation. In women, awe led to greater perception of the other as complex. Overall, these results indicate that there are broaden and build effects of positive emotions, but these are specific to both the emotion and the sex of the interaction members. This is also the first study to demonstrate both an actor and a partner effect of smiling on cooperation in a prisoner’s dilemma. An important area for further inquiry will be the interaction of emotion and sex in predicting social behavior. While sex differences in responding to threats have been characterized by the “tend and befriend” versus “fight or flight” action patterns, a similar approach may also need to be developed for sex differences in response to opportunities.