during an event organized to commemorate the 40th anniversary of the creation of the first undegraduate program in International Relations in Brazil at the University of Brasilia.The keynote speech, deliverd by Andrew Hurrell on the subject of pluralizing IR, was like a seed falling into a soil fertile with the discussions that were already taking place at the Institute of International Relations, particularly in light of recent disciplinary developments that have highlighted the importance of history, geography and culture for problematizing the "international".The November 2014 seminar, "Many Worlds, Many Theories?", in which Nicholas Onuf and Arlene B. Tickner participated, became the basis for launching the Call for Papers.Although the existence of "one world" and "many (or rival) theories" is a fairly well-known claim in the field of International Relations (Walt 1998, Snyder 2004), few alternative approaches have actually been recognized as constituting competing but equally authoritative (meaning scientific) readings of world politics.At IR's core, the view that there are three main "families" of theories (realism, liberalism and constructivism), and that the discipline has evolved along two sets of debates between neorealism and neoliberalism, and rationalism and reflexivism, continues to prevail.And yet, the idea of a "one world" world at the root of the positivist mainstream is under increasing challenge.Posed initially by R.B.J. Walker in his seminal book, One World, Many Worlds: Struggles for a Just World Peace (1988), the possibility that international relations, understood as both