Within international relations theory, there is significant disagreement on the nature and significance of leaders’ dispute outcome preferences. While many variants of realism assume that such preferences are relatively fixed and homogeneous, both the liberal and the constructivist schools view them as significant variables. This debate remains unresolved because, for the standard large-sample conflict data sets, there are no direct measures of leadership preferences over outcomes in given types of international disputes. Using a conflict bargaining experiment, we ask whether, after controlling for the effects of relative power and initial conditions, leadership preferences have a statistically significant impact. We use two different country samples—from China and the United States—to examine whether the impact of leadership preferences varies internationally. We find that realist-style preferences are a special rather than a general case, and that such differences have significant implications for understanding continuities and changes in Chinese and US foreign policies.