Saul Kripke’s discussion of the necessary a posteriori in Naming and Necessity and “Identity and Necessity” – in which he lays the foundation for distinguishing epistemic from metaphysical possibility and explaining the relationship between the two – is, in my opinion, one of the outstanding achievements of twentieth-century philosophy. My aim in this essay is to extract the enduring lessons of his discussion, and disentangle them from certain difficulties that, alas, can also be found there. I will argue that there are, in fact, two Kripkean routes to the necessary a posteriori – one correct and philosophically far-reaching, the other incorrect and philosophically misleading.