I argue that we can achieve certainty about some empirical propositions. When someone is having a migraine and attending to it, she can be certain that she is in pain. I show that examples intended to undermine claims of certainty or to raise doubts about the reliability of introspection do not touch such cases. Traditional foundationalists have held that epistemically certain beliefs can serve as the basis for all one’s other justified beliefs. This isn’t so, because those beliefs that are certain are spread too thinly to serve as broad justificatory foundations. Certainty has a different role. The best explanation for the existence of epistemically certain empirical beliefs is experientialism, the view that nondoxastic sensory experiences can justify beliefs. Experientialism then offers a framework for showing how the stream of sensory experiences can provide an adequate basis for the justification of our ordinary beliefs about the external world.