Hilary Putnam (1981) provides an anti-skeptical argument motivated by semantic externalism. He argues that our best theorizing about what it takes to experience, think, and so on, entails that the world is much as we take it to be. This fact eliminates the possibility of radical skeptical scenarios, where from our perspective everything seems as it does in the actual case, but we are widely and systematically mistaken. I think that this approach is generally correct, and that it is the most promising strategy for undermining radical skepticism. There are, however, well-discussed difficulties with Putnam's way of pursuing this strategy (see especially Anthony Brueckner 1986). I argue that in order to avoid these objections we will have to be more radical externalists than Putnam proposed; in particular, we will have to be perspectival externalists. According to perspectival externalism, a subject's reliable relations to her environment play a crucial role in determining not only the contents of her mental events, but also what it is like for her to grasp those contents. While semantic externalism is widely accepted in epistemology, perspectival externalism is not. I argue that perspectival externalism is independently more plausible than mere semantic externalism, and that such an account can enable us to better pursue Putnam's anti-skeptical strategy.