Negotiators often make errors in judgment that lead to suboptimal negotiated agreements. Although researchers agree that these errors result from "fixed pie" expectations, there is disagreement regarding how "fixed pie" expectations lead to poor outcomes. One view suggests that suboptimal agreements result when negotiators accurately process faulty and incomplete information (information availability errors); a second view holds that poorly negotiated agreements result when negotiators inaccurately process valid or complete information (information processing errors). The two experiments described in this paper confirmed that negotiators′ "fixed pie" expectations lead to suboptimal agreements via both information availability and information processing errors.