Given the recognition of the seriousness of climate change and other forms of environmental challenges, a growing number of political scientists are working in the environmental area. We have a substantial body of research examining local, regional, and global environmental issues. It is our sense that time is ripe for the field of international and comparative environmental politics to reflect on existing work, integrate it, and clearly articulate directions for future research. This special issue seeks to encourage scholars to systemically examine the roles of domestic and international factors, either alone or in interaction, to develop more nuanced models of environmental politics across space and time. We hope that the papers here will help to define the research frontier for the environmental politics field. Collectively, they exemplify recent efforts in comparative and international environmental politics that are, first, explanatory in orientation; second, cross levels of analysis in a way that transcends artificial subdisciplinary distinctions; and finally, are based on application of a variety of research methods and modeling techniques standard among the wider political science community.