Over the last three decades, the number of international environmental agreements into which states have entered has proliferated enormously. In the 1970s it was commonly assumed that the cumulative impact of such agreements would be to undermine the institution of state sovereignty. Recent evidence, however, suggests that the trend toward international cooperation in the face of “the seamless web of nature” has resulted in something more subtle but perhaps equally profound: a shift in the practices and norms of sovereignty. This essay looks at the impact of international environmental problem solving on state sovereignty. As a prelude, it reviews recent literature from international relations theory that substantiates a more differentiated view of sovereignty, separating it into three components: authority, control, and legitimacy. With this more complex notion of sovereignty as a backdrop, the review argues that the proliferation of environmental agreements has in fact led to a complex web of “sovereignty bargains” through which states have increased their sovereignty vis-a-vis certain dimensions even as they have suffered losses of sovereignty vis-a-vis others. Although more research remains to be done, environmental cooperation appears to have indeed altered the nature and practice of sovereignty in the contemporary world.