This paper surveys the recent literature on the political economy of the formation of international environmental agreements. The survey covers theoretical modelling approaches and empirical studies including experimental work. Central to our survey is the question how the political process impacts different stages of agreement formation and stability. Relevant are the rules defined during pre-negotiations that govern negotiations, ratification and implementation. Strategic delegation and lobbying are directly relevant during the negotiation and ratification phases. Implementation, the choice of policy instruments at the national level, will also be impacted by lobbying and indirectly influence negotiations.