The world is marked by multiple crises and challenges that transcend borders and require not only local but global solutions. Only by working together and bridging divides and differences can countries address these challenges and drive a sustainable development future for all. This report by the OECD and the Islamic Development Bank demonstrates triangular co-operation’s relevance for delivering progress on sustainable development. In particular, it stresses its innovative approach to diplomacy, and its ability to bring together different stakeholders from across the global south and north in trusting partnerships that leverage the expertise, knowledge and resources of all partners. The report also examines the current global trends in the use of triangular co-operation, explores how to strengthen national ecosystems to support its effective delivery, and highlights how triangular co-operation can contribute to addressing climate change and biodiversity loss, with a specific focus on small island developing states.