Strict libertarianism, as one of us has defined it elsewhere, is “a radical political view which holds that individual liberty, understood as the absence of interference with a person’s body and rightfully acquired property, is a moral absolute or near-absolute, and that the only governmental activities consistent with that liberty are (if any) those necessary to protect individuals from aggression by others.” Strict libertarianism is a radicalized form of classical liberalism that is, characteristically, rationalistic, monistic, and (relatively) absolutist in its approach to political principles. One advantage of bringing so many well-informed proponents and critics of libertarianism together in the same volume is that it makes clear the tremendous diversity of libertarian thought. Libertarians are a methodologically, normatively, and even politically diverse group. The chapter also provides an overview of the key concepts discussed in this book.