Book excerpt: Libertarians often bill their theory as an alternative to both the traditional Left and Right. The Routledge Handbook of Libertarianism helps readers fully examine this alternative without preaching it to them, exploring the contours of libertarian (sometimes also called classical liberal) thinking on justice, institutions, interpersonal ethics, government, and political economy. The 31 chapters--all written specifically for this volume--are organized into five parts. Part I asks, what should libertarianism learn from other theories of justice, and what should defenders of other theories of justice learn from libertarianism? Part II asks, what are some of the deepest problems facing libertarian theories? Part III asks, what is the right way to think about property rights and the market? Part IV asks, how should we think about the state? Finally, part V asks, how well (or badly) can libertarianism deal with some of the major policy challenges of our day, such as immigration, trade, religion in politics, and paternalism in a free market. Among the Handbook's chapters are those from critics who write about what they believe libertarians get right as well as others from leading libertarian theorists who identify what they think libertarians get wrong. As a whole, the Handbook provides a comprehensive, clear-eyed look at what libertarianism has been and could be, and why it matters.