Almost two decades have passed since ‘emerging donors’– new providers of development cooperation – began to attract the attention of ‘traditional donors'. Comprehensive comparisons of the various features of different types of donors have thus been elaborated on as their economic and political roles have solidified. Subsequently, the focus has also expanded to cover the growing significance of cooperation between ‘new donors’ themselves, beyond high-profile groups such as the BRICS (Brazil, Russia, India, China, and South Africa). This issue of the IDS Bulletin is a collaboration between the Japan International Cooperation Agency (JICA) Research Institute and the Institute of Development Studies (IDS). The studies are dedicated to highlighting the actual and potential contribution of a wider range of donors, and are intended to help compensate for imbalances in existing literature, contribute to scholarly understanding, and offer informative insights for practical policy deliberation. More fundamentally, this issue questions the explicit and implicit underlying assumptions in examining the issue of development cooperation: namely, the dichotomy of ‘traditional’ and ‘emerging’ donors. The subjects covered in the various articles range from exploring the importance of knowledge in the development cooperation experience of emerging economies; the challenges involved in the policy formulation and implementation of triangular cooperation within a sometimes contradictory set of processes embedded in South–South cooperation; the dynamics of ‘two-way interaction’ between donors and recipients in chains of knowledge creation; and there is an important reassessment of the critical data upon which estimates of China’s foreign aid disbursements are made and understood in international comparison.