Hassig first presents the traditional explanation of the Aztec calendrical system and its ideological functions and then marshals contrary evidence to argue that the Aztec elite deliberately used calendars and timekeeping to achieve practical political ends. He further traces how the Conquest played out in the temporal realm as Spanish conceptions of time partially displaced the Aztec ones. His findings promise to revolutionize our understanding of how the Aztecs and other Mesoamerican societies conceived of time and history.