This article examines the discourses on the fragmentation and diversification of environmental governance through frames offered by the English School (ES) of International Relations (IR) scholars in order to apply their frame to climate change governance. It argues that the ES approach emphasises the pluralist starting-points of international law and governance. This article does not try to analyse pros and cons of fragmentation and diversification, rather, it examines whether the society is ‘thin’ or ‘thick’ regarding climate change governance. To what extent can the climate change practices established be spoken of as primary institutions? This is significant in order to weigh the future developments of governance. In the last section of the article, this discussion is realised by examining the developments of climate change governance both within and without the context of the UN Framework Convention for Climate Change (UNFCCC).