The publication of the Origin of Species propelled Darwin to the status of a public figure, and although he himself preferred to remain secluded in his country house at Downe and pursue specialised research, his theory was at the centre of a heated debate on the social and political implications of evolution. The key principles of Darwin’s biology - the struggle for existence and natural selection - became subject to a wide spectrum of interpretations ranging from laissez-faire liberalism to Marxism. This state of affairs raises some interesting questions concerning the claims and arguments advanced by proponents of such opposing views in defence of their positions. Simultaneously, one may inquire after Darwin’s own political opinions. This chapter proposes to examine these questions through a close study of reactions to the publication of the Origin from three different sources: first, the somewhat misleading enthusiasm of Herbert Spencer, the great philosopher of evolution and an advocate of an extreme type of individualism; second, the progressive attitude of Clémence Auguste Royer, the first translator of Darwin’s Origin into French; and finally, the comments made by the authors of the Communist Manifesto, Karl Marx and Friedrich Engels. All three offer particularly interesting case studies, since Darwin expressed his own opinions of their claims regarding his theory, mostly in private correspondence.