Toleration is one of the most foundational and contentious concepts in contemporary political discourse. Although its modern origins lie in the realm of religious dissent, toleration remains one of our most contentious and broad-ranging concepts, invoked in today's debates about race, gender, religion, sexuality, cultural identity, free speech, and civil liberties. Questions of toleration arise wherever unpopular groups face hostile environments and stand in need of protection from state interference or the actions of their neighbors. Toleration can seem counterintuitive at first glance, since it involves a complex mixture of rejection and acceptance, combining disapproval - of particular individuals, groups, beliefs, and practices - on the one hand with legal and political guarantees for such groups on the other. Toleration has long been considered a cardinal virtue of liberalism, endorsed by central figures such as Locke, Mill, and Rawls. Although toleration has been criticized as unduly minimal, compared with more expansive terms such as recognition or acceptance, it has routinely played a key role in the protracted struggles of marginalized groups of various sorts (a necessary, if not always sufficient, condition for liberty). Toleration: A Very Short Introduction will concisely canvass the history, development, and contemporary global status of toleration as both a concept and a contested political and legal practice.