Abstract: In the last ten or fifteen years, realism has emerged as a distinct approach in political theory. Realists are skeptical about the merits of abstract theories of justice. They regard peace, order, and stability as the primary goals of politics. One of the more concrete aims of realists is to develop a realist perspective on legitimacy. I argue that realist accounts of legitimacy are unconvincing, because they do not solve what I call the “puzzle of legitimacy”: the puzzle of how some persons can have the right to rule over others, given that all persons are equals. I focus on the realist accounts of legitimacy developed by Bernard Williams and John Horton.