This article outlines how the global development set-up looks today. The picture is of a complex “ecosystem”, with many different types of organisations delivering assistance in a variety of different forms. This complexity presents both opportunities and threats to the developing countries on the receiving end. Without some oversight and guidance, the system could become burdensome and inefficient. The article describes how the DAC is in a unique position to keep track of the trends and to help to bring harmony to the system. It describes these issues in relation to the more than 200 “multilateral donors” – such as the United Nations, the World Bank and the global funds – which today receive or serve as a channel for 40% of all aid. The challenge is to ensure this is being delivered effectively and that efforts are as co-ordinated as possible, both with each other and with the priorities of the developing countries in which they work. As an example, the latest global plans to tackle climate change are a test case for the development community: the article explores how this can be done without increasing the complexity further.