Dictatorship comparison studies are rare in German history of education research. This contribution attempts such an analysis by considering the National Socialist State and the German Democratic Republic schools. The comparison of school organization and structure on the one hand, of their effects on the other hand, show which are the similarities with respect to the political power grasp on different aspects, such as curriculum and undesired teachers; it also reveals differences, especially with respect to inclusion and exclusion processes, or to the consequences of their respective ideologies, i.e. of «race» versus of «class». Both German dictatorships have in common the gap between the intended and the actual political hold on the educational system. We attempt to explain this discrepancy with the assumption that school has its own and specific logic.