The last decade has witnessed a new wave of interest in the role of culture(s) in foreign affairs. Claims that the international order could undergo a clash between competing cultures have sadly returned to the headlines (Rachman, 2019). In the West, nativist politics has challenged cosmopolitan views in ways unprecedented in the post-Cold War order. Huntington's (1996) ideas have returned to the charge, either as an alleged confirmation of the American scholar's civilisation waves or, more frequently, as an attempt to critique his claims. In a best-selling novel, Michel Houellebecq (2015) depicted the alleged submission of French society to a patriarchal Muslim party that wins the Presidential elections. Amidst the 2022 Russian invasion of Ukraine, the attempts to erase Ukrainian identity and the promotion of Russian imperialism through cultural icons have received close scrutiny (i.e. Tsurkan, 2022;Valenza, 2023b). Overall, the already existing fears that the decline of the Western-based international order could end the cultural consensus around it have increased in the post-February 24 world.Despite this unexpected revival and interest in the subject, culture remains, somewhat paradoxically, the underdog of international relations (IR), including within regional cooperation studies. IR theories tend to privilege traditional conceptions of cultures as bounded systems of meanings and hence neglect the role they play in the construction of international orders. Existing works have mainly explored single case studies and analysed cultural policies implemented by regional organisations (see the next section).In line with an emerging scholarship challenging these essentialist and reductionist visions, this chapter looks at cultural policies as tools that in the framework of regional cooperation help organise cultural diversity and privilege some meanings and repertoires of practices at the expense of others (Reus-Smit, 2018). By recognising from the outset that there is no such thing as an 'organic culture', we seek to uncover whether and to what extent regional order-builders -regional institutions, national governments, or any other relevant actor -resort to nativist or pluralist conceptions through cultural cooperation. Whereas, broadly speaking, nativist conceptions conceive cultures as coherent and bounded systems of meanings, in pluralist conceptions diversity is not only managed but also integrated as a founding principle, thus refuting essentialist understandings of cultures.The chapter explores through comparative discourse analysis cultural policies in four regional organisations: the European Union (EU); the Commonwealth of Independent States (CIS); the Common Market of the South (MERCOSUR in Spanish); and the Andean Community (CAN in Spanish). All organisations have resorted to cultural cooperation in their framework, although the rationale and the stages of development have differed widely. In line with the theoretical approach sketched out, we find that regional organisations operate as 'diversity reg...