We build on the small but growing literature documenting personality influences on negotiation by examining how the joint disposition of both negotiators with respect to the interpersonal traits of agreeableness and extraversion influences important negotiation processes and outcomes. Building on similarity-attraction theory, we articulate and demonstrate how being similarly high or similarly low on agreeableness and extraversion leads dyad members to express more positive emotional displays during negotiation. Moreover, because of increased positive emotional displays, we show that dyads with such compositions also tend to reach agreements faster, perceive less relationship conflict, and have more positive impressions of their negotiation partner. Interestingly, these results hold regardless of whether negotiating dyads are similar in normatively positive (i.e., similarly agreeable and similarly extraverted) or normatively negative (i.e., similarly disagreeable and similarly introverted) ways. Overall, these findings demonstrate the importance of considering the dyad’s personality configuration when attempting to understand the affective experience as well as the downstream outcomes of a negotiation.