This volume is the first of an ambitious two-volume book project on Global Regionalism. The project consists of a collection of around 100 essays examining the past, present, and future of regionalism studies, as well as the continued relevance of regional governance. It is presented on the occasion of the 25th anniversary of the United Nations University Institute on Comparative Regional Integration Studies (UNU-CRIS) and counts on the collaboration of a diverse group of authors from all over the world, both established senior and upcoming junior scholars. The central question driving the book project is about the need and feasibility of globalising regionalism studies, and echoes the debates on global IR, in turn echoing similar debates in the wider social sciences. In various parts of the two volumes, contributors explore the diverse origins of regionalism thinking, examine the continued relevance (or not) of mainstream theories, imagine and propose building blocks for a global regionalism discipline, and assess the continued relevance of regions and regional governance in today’s and tomorrow’s world. The contributors present their ideas in the form of short essays or think pieces.