This chapter examines how states have very different preferences in global environmental politics. These state preferences are formed and shaped in a co-evolving process at both the domestic and international levels. Domestically, a rational choice analysis shows how environmental vulnerability and the costs of abatement contribute to defining a state's national interests in environmental politics. But the rational choice model, though useful, has its limits. It often presents the state as a unitary and monolithic actor, whereas in fact states come in multiple institutional forms and are made up of numerous actors with varying and sometimes conflicting interests. Several international factors also play an important role in shaping state preferences. Some of those international factors revolve around how states interact with one another in international negotiations. Indeed, state preferences can be revised during international negotiations via states' interactions in working and contact groups, with negotiating chairs, in coalitions, and through leadership efforts.