It is widely held in philosophy that knowing is not a state of mind. On this view, rather than knowledge itself constituting a mental state, when we know, we occupy a belief state that exhibits some additional non-mental characteristics. Fascinatingly, however, new empirical findings from cognitive neuroscience and experimental philosophy now offer direct, converging evidence that the brain can—and often does—treat knowledge as if it is a mental state in its own right. While some might be tempted to keep the metaphysics of epistemic states separate from the neurocognitive mechanics of our judgements about them, here I will argue that these empirical findings give us sufficient reason to conclude that knowledge is at least sometimes a mental state. The basis of this argument is the epistemological principle of neurocognitive parity—roughly, if the contents of a given judgement reflect the structure of knowledge, so do the neurocognitive mechanics that produced them. This principle, which I defend here, straightforwardly supports the inference from the empirical observation that the brain sometimes treats knowledge like a mental state to the epistemological conclusion that knowledge is at least sometimes a mental state. All told, the composite, belief-centric metaphysics of knowledge widely assumed in epistemology is almost certainly mistaken.