Abstract An apparent lack of similar cases has shaped how observers compare integration in Europe with other regions. The growing field of comparative regionalism, however, has overlooked three decades of sustained economic integration between Australia and New Zealand. This article introduces trans-Tasman integration as a new empirical case of regional economic integration. It compares trans-Tasman integration with European experience with reference to deepening economic integration and supranational institutional arrangements, and explores similarities and differences with other regional arrangements. Adding this second case of deep integration to the comparative field enhances the understanding of regional integration in different contexts.