Socio-environmental conflicts are widespread, and global economic growth will likely increase them in the coming decades. While political ecology, the analysis of common pool resources, and ecological economics, among others, have provided praiseworthy insights into such conflicts, institutional approaches to these phenomena are still scarce. Classical institutional economics has occasionally been put to work on environmental issues, but proposed frameworks remain relatively underdeveloped. We wish to contribute to institutional research on environmental issues by building upon Bruno Thérets interpretation of John R. Commonss transactional model and applying the framework to a case of socio-environmental conflicts. First, we briefly sketch the landscape of institutional contributions (especially those that follow the classical institutionalist tradition) to the analysis of environmental issues. We explain why Commons has largely been ignored on these issues. Then, we analyze some of the key concepts of Commonsian economics that are of particular interest to our theoretical elaboration. Following this, we depict Commonss transactional scheme and propose an application to a case of socioenvironmental mining conflict in Peru. Our framework could complement existing ones and shed light on the institutional dynamics of natural-resource management through conflict.