While there are profound disagreements about how more sustainable forms of living might be achieved, most research on pro-environmental action recognizes it as a fundamentally social challenge—demanding shifts not merely in individuals’ attitudes and behaviors, but also in social norms, contexts, and practices. Despite the social nature of the challenge, perhaps the most fundamental social medium—social interaction—remains undertheorized in this area. To address this gap, this article applies Erving Goffman's understandings of social interaction to an ethnographic case study of a pro-environmental change initiative called Environment Champions. The analysis shows that social interaction plays a crucially important role in shaping responses to pro-environmental change processes, a role that has the potential to both help and hinder the spread of pro-environmental action. The article concludes by exploring how Goffman's ideas develop and extend current debates about pro-environmental behavior change. 2015