In the past half-century, the practice and study of global environmental politics and governance have been dramatically rescaled. They have become increasingly complex and interconnected with respect to the level (between local and global) at which they take place, the range of actors engaged in them, and the linkages between them and nominally nonenvironmental issues. Global environmental politics and governance have been rescaled vertically down toward provincial and municipal governments and up toward supranational regimes. They have also been rescaled horizontally across regional and sectoral organizations and networks and across new issues, such as development, security, and trade among others. This rescaling reflects shifts in the magnitude, complexity, and interconnectedness of the global environmental problems humans face as well as epistemological shifts in how humans understand and respond to these problems, and rescaling has implications for both the practice and study of global environmental politics.