Scholars have long debated whether nuclear superiority or the balance of resolve shapes the probability of victory in nuclear crises, but they have not clearly articulated a mechanism linking superiority to victory, nor have they systematically analyzed the entire universe of empirical cases. Beginning from a nuclear brinkmanship theory framework, I develop a new theory of nuclear crisis outcomes, which links nuclear superiority to victory in nuclear crises precisely through its effect on the balance of resolve. Using a new data set on fifty-two nuclear crisis dyads, I show that states that enjoy nuclear superiority over their opponents are more likely to win nuclear crises. I also find some support for the idea that political stakes shape crisis outcomes. These findings hold even after controlling for conventional military capabilities and for selection into nuclear crises. This article presents a new theoretical explanation, and the first comprehensive empirical examination, of nuclear crisis outcomes.