The negotiating group of developing countries, the G77, is one of the most important institutions in global climate governance. This article analyses the cohesiveness of, and internal tension within, the G77 coalition by using the politics of climate change as the empirical window. The study examines four arenas of UN-based deliberations on climate change in the years 2007–2010; the Security Council, the Commission on Sustainable Development, the General Assembly and the United Nations Framework Convention on Climate Change (UNFCCC). We argue that these deliberations, once they reached the top of the international political agenda in 2007, and ever since, have posed deeper challenges to the G77 coalition than ever before. While developing country interests are both converging and diverging, the increasingly conflicting interests, as well as the very slowly eroding common identity, are creating increasingly unified subgroups in the G77. The G77 is highly unlikely to break up formally, but how functional it will be as a bloc in the forthcoming climate change negotiations remains an open question.