Both Gideon Rose's neoclassical realism and Andrew Moravcsik's liberalism attempt to solve the problem of how to incorporate domestic factors into international relations theory. They do so in very different ways, however. Liberalism is a “bottom-up” perspective that accords analytic priority to societal preferences; neoclassical realism is a “top-down” perspective that accords analytic priority to systemic pressures and treats domestic factors as intervening variables. These two approaches are not equivalent, and the choice between them has high stakes. Although it has gained rapidly in popularity, neoclassical realism is fundamentally flawed. Its intellectual justification is weak; it is logically incoherent; and it induces the commission of methodological errors. Realism can incorporate certain domestic factors without losing its theoretical integrity, but it does not need and should not use neoclassical realism to do so.