One of the most striking features of the work of scientists specialized in regional environmental governance is the huge diversity of ways they refer to the notion of region. In this academic subfield, “regionality” refers to different orders of reality (ontology), and regions have a heterogeneous status in the production of knowledge (epistemology). While such a diversity of uses and meanings illustrates the rich potential of a regional scope in environmental governance analysis, scholars' ontological and epistemological stances must be made more explicit. The objective of this commentary is to elaborate this suggestion and to illustrate it on the basis of the articles published in this special issue.