We demonstrate that a person's eye gaze and his/her competitiveness are closely intertwined in social decision making. In an exploratory examination of this relationship, Study 1 uses field data from a high-stakes TV game show to demonstrate that the frequency by which contestants gaze at their opponent's eyes predicts their defection in a variant on the prisoner's dilemma. Studies 2 and 3 use experiments to examine the underlying causality and demonstrate that the relationship between gazing and competitive behavior is bi-directional. In Study 2, fixation on the eyes, compared to the face, increases competitive behavior toward the target in an ultimatum game. In Study 3, we manipulate the framing of a negotiation (cooperative vs. competitive) and use an eye tracker to measure fixation number and time spent fixating on the counterpart's eyes. We find that a competitive negotiation elicits more gazing, which in turn leads to more competitive behavior.