It is difficult to think of a more significant example of international co-operation to address a problem that threatened the health and wellbeing of the entire planet than the 1987 Montreal Protocol for the Elimination of Ozone-Depleting Substances. This breakthrough in international environmental governance has proved to be an extraordinary success beyond rhetoric or promises. What happened and why is of tremendous importance for those looking for guidance in the future, particularly those now involved in hugely complicated negotiations on climate change. The success of the Montreal Protocol has been linked to many factors such as political will, treaty flexibility and the recognition of equity issues raised by developing countries. This highly original and provoking thesis synthesises some of the more exciting social science concepts and methods, while refining our basic understanding of environmental social change and providing policy-makers with concrete success factors to replicate.