The book explores different questions, for example the status and role of BRICS in the changing international order; how countries in the Global South can use regionalism to change the world order; the competing worldviews that manifest themselves in the institutional variety of regionalism; and, most importantly, how all these changes push International Relations as a field to become more global, or at least to go beyond Westphalian thinking - thus bringing the role of multilateralism back to the discussion. The book critically analyzes the ongoing changes in the regional, intra-regional, and global dynamics of cooperation, from a multi-disciplinary and pluralist perspective. It is based on the insight that in a post-hegemonic world the formation of regions and the process of globalization can be largely disconnected from the orbit of the US, and that a plurality of power and worldviews has replaced US hegemony. In spite of these changes, most existing analyses of current changes in the world order still rely upon Western-centered approaches, and Westphalian thinking. Against this backdrop, the book proposes to advance a truly global IR understanding of the post-hegemonic world, and weaves together the pluralist and multi-disciplinary perspectives of scholars located all around the world.