Does environmental lobbying affect the probability of environmental treaty ratification? Does the level of government corruption play a role for the success of such lobbying? In this paper, we propose that a more corruptible government may be more responsive to the demands of the environmental lobby. We use several stratified hazard models and panel data from 170 countries on the timing of Kyoto Protocol ratification to test this hypothesis. We find that increased environmental lobby group activity raises the probability of ratification, and the effect rises with the degree of corruption.