Since 1833, the Society for Schleswig-Holstein History (GSHG) has documented regional, social, and political changes, of which this oldest historical society in Schleswig-Holstein was not exempt. This study focuses on the impact of the political upheavals of 1918/19 and 1933 on the work of the GSHG and on the self-understanding of its leading members, as well as the question of whether it was possible to keep scientific and publishing activities free from political influence during the period from 1918 to 1945. Thus, it not only represents the first investigation into the activities of the GSHG during the Weimar Republic and the National Socialist era but also contributes to the debate on the role of German historians during this time, particularly in the field of non-university institutions.