The aim of the proposed project is to determine and explain the drivers and constraints of climate ambition among the parties to the Paris Agreement. Central to this endeavour is the question of whether or not the Paris Agreement manages to function as a catalyst for increased ambition, or whether ambition levels are solely explained by domestic determinants. Through this approach, the proposal builds on the disconnect between comparative climate policy literature and global governance literature, dipping into the ‘black box’ of domestic politics to enhance theories of global climate governance. To find an answer to this research question, a set of theoretical implications are derived from the catalytic cooperation model and juxtaposed to an explanatory regression model representing the political economy of climate ambition. An database of the ‘Nationally Determined Contributions’ will be constructed based on a mixed-method text-analysis and will serve as a foundation for testing both the regression model and the theoretical implications in a statistical analysis. If the analysis confirms that the model of catalytic cooperation holds true for the Paris Agreement, common conceptions of climate change and climate change governance have wrongly been based on collective action and freeriding issues for decades.