The definitive version is available at www.blackwell-synergy.comI offer a model of self-knowledge that provides a solution to Moore's paradox. First, I distinguish two versions of the paradox and I discuss two approaches to it, neither of which solves both versions of the paradox. Next, I propose a model of self-knowledge according to which, when I have a certain belief, I form the higher-order belief that I have it on the basis of the very evidence that grounds my first-order belief. Then, I argue that the model in question can account for both versions of Moore's paradox. Moore's paradox, I conclude, tells us something about our conceptions of rationality and self-knowledge. For it teaches us that we take it to be constitutive of being ra...