This dissertation develops and defends a view of the relationship between knowledge and norms on action. The view I defend is an impurist one; on this view, whether a person knows that p can depend on factors that are unrelated to the truth or likelihood of p. On my impurism, normative facts about actions and options—including, for instance, the costs of relying on a belief in action—are among the non-truth-related factors that can make a difference to knowledge. My view is distinctive, in part, because of the further claim that moral facts about actions and options are among the normative considerations that can make a difference to knowledge. In a slogan: epistemic norms are sensitive to moral considerations. In an even shorter slogan: there is moral encroachment in epistemology. The first half of the dissertation defends the claim that there is moral encroachment in epistemology. In chapter 1 (“Pragmatic Encroachment and Moral Encroachment”), I argue that moral encroachment is at least as well-motivated as a more familiar view: the view that there is pragmatic encroachment in epistemology. In chapter 2 (“Uncertainty, Belief, and Ethical Weight”), I draw on insights from moral psychology to provide an original argument for moral encroachment.The second half of the dissertation starts from the assumption that there is moral encroachment in epistemology. It is devoted to describing in detail how moral encroachment works. In chapter 3 (“Moral Encroachment and Reasons of the Wrong Kind”), I distinguish between a radical and a moderate version of moral encroachment. I raise a problem for the radical version: it threatens to erase the distinction between epistemic and non-epistemic norms on belief. This problem, I note, does not afflict the moderate version of moral encroachment. In chapter 4 (“Knowledge and the Many Norms on Action”), I show that it is no trivial task to explain why knowledge is sensitive to both moral norms and norms of practical coherence. In fact, I argue, existing versions of impurism generally lack the resources to provide the needed explanation. I also make some suggestions about the best ways to for an impurist to meet this challenge.It’s clear that impurists both can and should add texture to their picture of norms on action. They can make significant headway by endorsing two of my primarily conclusions. First: there are multiple distinct families of normative considerations (including, for instance, moral considerations and considerations of practical coherence) that are equally well-placed to make a difference to knowledge. And second: only some of the moral considerations that bear on belief are apt to make a difference to knowledge. These conclusions point the way toward a clearer picture of an impurism worth defending.