The mass murder of mentally disabled and psychiatric patients in National Socialist Germany, which claimed around 300,000 fatalities, opened up entirely new possibilities for psychiatric research. This chapter outlines the role of the professional association of scientists at the interface between science and politics. The Society of German Neurologists and Psychiatrists was created in 1935, when the German Association for Psychiatry merged with the German Association for Mental Hygiene and the Association of German Neurologists. Pulling the strings in the background was a tightly knit network centred on Ernst Rudin, who was director of the German Institute for Psychiatric in Munich since 1931; he was considered the leading scientist in the field of psychiatric genetics in Germany. The point of departure of the research plan designed by Rudin was the by then classical question of eugenics after the damaging effects of counter-selection caused by the war. A central aspect of Rudin's plan elaborated on the "euthanasia" measures still under way.