In light of the growing attention that social norm interventions have garnered as policy tools, we review the current body of evidence on their effectiveness with respect to pro-environmental behaviors. We identify the various conceptualizations of social norms currently in use and inventory the experimental economics and social psychology literature that has examined the impacts of social norm interventions on pro-environmental behavior. For each study included in this inventory, we note several contextual features, the data collection and analytical methods used, and any significant main effects attributed to the social norm intervention. We also review several theoretical models of behavior that incorporate social norms. Based on this empirical and theoretical review, we draw a number of policy implications and identify avenues for future research on the role of social norms with respect to pro-environmental behavior.