Until the end of the twentieth century, the Leuvenum estate in the north-western Veluwe and the De Bannink estate in the south-western Salland were owned by the noble family Sandberg. The twentieth century management of these estates is strongly characterized by an exceptional ownership and management situation, which arose at the end of World War II, when following the death of the owner and his son, his widow and daughters took over the estates’ management. At the same time, changes occurred in the economic exploitation, in the social relationships and in the cultural significance of large land ownership, all of which impacted estate management. How estate management developed in the broader context of the transformation of the Dutch countryside in the twentieth century is a topic that has so far received too little attention. However, it is an extremely interesting period marked by large-scale economic and agricultural developments, changes in our ideas about nature, landscape protection and heritage management, and by processes of democratization in Dutch society. These developments led to decisive changes in the existing power and ownership structures and to unknown transformations of the countryside. Throughout an eventful century, the noble Sandberg family endured. Although an integral characterization of estate ownership and management is impossible without considering the influence of World War II, this study shows how decisive external factors were for these open and pluriform systems. Moving with the societal, economic, agricultural, and demographic developments was a prerequisite for standing the test of time.