The chapter tackles the complex, tension-ridden, and often paradoxical relationship between relativism and conservatism. We focus particularly on radical conservatism, an early twentieth-century German movement that arguably constitutes the climax of conservatism’s problematic relationship with relativism. We trace the shared genealogy of conservatism and historicism in nineteenth-century Counter-Enlightenment thought and interpret radical conservatism’s ambivalent relation to relativism as reflecting this heritage. Emphasizing national particularity, historical uniqueness, and global political plurality, Carl Schmitt and Hans Freyer moved in the tradition of historicism, stopping short of full relativism. Yet they utilized relativistic elements – such as seeing irrational decisions or the demands of “life” as the basis of politics – to discredit notions of universal political morality and law, thereby underpinning their authoritarian agendas. Oswald Spengler, by contrast, took the relativistic impulses to the extreme, interweaving his conservative authoritarianism and nationalism with full-fledged epistemic, moral, and political relativism. Martin Heidegger has recently been perceived as the key philosopher of radical conservatism, and his thought arguably channeled antimodern aspects of historicism into contemporary political thought. We conclude by analyzing how some radical conservative arguments involving cultural relativism and plurality still reverberate in contemporary theorists such as Samuel Huntington, Aleksandr Dugin, and Alain de Benoist.