The authors developed and tested a model proposing that negotiator personality interacts with the negotiation situation to influence negotiation processes and outcomes. In 2 studies, the authors found that negotiators high in agreeableness were best suited to integrative negotiations and that negotiators low in agreeableness were best suited to distributive negotiations. Consistent with this person-situation fit argument, in Study 1 the authors found that negotiators whose dispositions were a good fit to their negotiation context had higher levels of physiological (cardiac) arousal at the end of the negotiation compared with negotiators who were "misplaced" in situations inconsistent with their level of agreeableness, and this arousal was in turn related to increased economic outcomes. Study 2 replicated and extended the findings of Study 1, finding that person-situation fit was related to physiological (heart rate), psychological (positive affect), and behavioral activation (persistence) demonstrated during the negotiation, and these measures in turn were related to the economic outcomes achieved by participants.