Despite growing international environmental interdependence, the international system lacks a central authority to foster environmental protection. As a consequence, countries have adopted different policies to reduce international environmental problems. More specifically, costly regulations are not universally supported. In order to explain the success and failure of international environmental regulation, it is necessary to systematically focus on the factors that shape the environmental foreign policy of sovereign states. Since such an approach is missing from the literature, we develop an interest-based explanation of support for international environmental regulation and postulate what impact it should have on state preferences for international environmental regulation. Specifically we apply our framework to two prominent cases of negotiations on atmospheric pollution control, namely, efforts to protect the stratospheric ozone layer and the regulation of transboundary acidification (“acid rain”) in Europe.