This paper argues that international society is characterized by two major, global tendencies of normative significance: an increasing political, economic and social interdependence, and a deep controversy between a sovereignty norm of non-intervention and a responsibility norm calling for transnational action to protect people across borders. The background for this tension should be found in history; in the Westphalian international system, and the traditional cosmopolitanist approach, respectively. Because of the rising level of interdependence, this battle between norms is played out on a broad field of international issues from security and humanitarian intervention to trade talks and economic development. Since the end of the Cold War the East-West divide has been substituted for a division between a North-West side acting upon a universalist, rights-based norm, and a South-East side defending sovereignty and pluralism. Some in the latter camp tend to regard humanitarian concerns of the North-West as a smoke screen for hegemonic, economic and strategic interests. In order to overcome this new division, both the sovereignty norm and the cosmopolitanist aspirations may have to be redefined through new ways of thinking legitimacy in international society.