The end of the Cold War witnessed a surge of regionalism, which triggered the proliferation of new research. While studies on the European Union (EU) used to dominate the field, developing distinctive concepts and theories, regionalism has gained prominence outside Europe. Students of area studies in particular felt that EU approaches had little to offer that could help them understand processes of regionalism in Africa or Asia. The so-called ‘New Regionalism’ literature has, therefore, taken a different approach that emphasizes the social construction of regions and the role of non-state actors other than pressure groups, as well as the importance of cultural and environmental aspects (Farrell et al. 2005; Hettne et al. 1999; Söderbaum and Shaw 2003). At the same time, international political economy (IPE) gave rise to another important body of research on regionalism, focusing on regional trade and investment patterns and the design of regional institutions to foster liberalization and settle disputes over market access. The main dependent variable of such IPE approaches is the emergence and effectiveness of preferential and free trade areas (PTA and FTA), whose number is sufficiently large to apply statistical methods to test various strands of (rational) institutionalist theories (inter alia Mansfield and Milner 1997; Mansfield and Reinhardt 2003; Milner 1988).