This chapter dwells on the calendar and more specifically on personal time management systems as a technology that mediates between the organization and the individual. The calendar is discussed as a technical medium of standardization and modularization as well as a medium of cultural synchronization, which provides an interface between the demands of an organization and those of its employees. Following Weber’s claim on the interrelatedness of capitalism and the Christian conduct of life, the calendar is discussed as a medium of Protestantism and as an integral part of the media and cultural history of the rationalization of the self.