This book analyses the so-called moral problem of authority, which is the challenge of reconciling legitimate authority (the right to rule) with the demands of freedom and rationality. It offers a critique of authority sceptics, both anarchist and non-anarchist, who insist that authority can never have legitimacy. It also points to problems with many conventional defences of authority, including those of deliberative democracy, which assume that insofar as authority is legitimate it simply satisfies the demands of freedom or rationality. In this book, through a close engagement with the work of Joseph Raz in particular, it is argued that authority can have legitimacy, but when it does it generates a moral dilemma, where the obligation to obey comes at some cost to freedom and reason.