Recognizing that social Darwinism is an intrinsically varied and composite concept, this essay advocates an approach delineating the various intellectual constituents and sociopolitical contexts. It is argued that German social Darwinism has often had a sophisticated biological content, and that the prevalent notion of the state as a biological organism has drawn on non-Darwinian biological theories. Different social interests and programs, institutional structures, and professional interests have also to be taken into account. Alternative interpretations stressing Nazi vulgarizations of biology have serious historical flaws. The paper considers the position of the historian Richard J. Evans, who has rejected interpretations of social Darwinism as scientific and medical discourse. While Evans stresses social Darwinism as public rhetoric, I suggest that social-Darwinist ideas have provided rationales for welfare policies and have had institutional, professional, and ideological implications. What occurred in crucial sectors of the emergent German “welfare state” was a shift from the legally trained administrators to specialists in such areas as public health and social work, who frequently looked to biology to legitimate policy.