Almost three decades ago, Keohane and Martin (1995) emphasised the promise of institutionalist theory. This essay seeks to do the same for mainstream theorising on regionalism. While Keohane and Martin replied to criticism from realist perspectives, mainstream theorising on regionalism is mainly criticised by researchers seeking to globalise International Relations (IR). Global regionalism strives to overcome Eurocentric biases in the study of regions by embracing diverse philosophical traditions, epistemologies, theories, concepts, and methodologies, emphasising local agency and seeking to acquire in-depth region-specific expertise.