Abstract: Cooperation problems result from a certain structure of incentives, in particular when what is in the self-interest of each agent in a group stands in tension with what is in the collective interest of the group of agents. To make sense of climate change as a cooperation problem between states, states have to be the kinds of things that have self-interest, and can have collective interests together with other states. In order to hold states morally (and perhaps legally) culpable for blocking international treaties, or making insufficient contributions to an important collective good like the reduction of greenhouse gas emissions, states must be capable of ongoing intentional action―must be at least agents, at most moral agents. Is there an interpretation of 'the state' on which all of these things can be true? Assuming that the state will be a collective rather than an individual agent (although I'll discuss both possibilities), which individual agents are implicated in that agency, for example in virtue of membership? What does this imply for thinking about culpability for states' actions?