The study of norms is of paramount importance in understanding human behavior. An interdisciplinary literature, using varying definitions and conceptions, shows when and why norms emerge and spread, what form they can take, and how they are enforced. Here, we focus on theoretical and empirical literature that treats norms as a factor influencing human behavior. We first present a new taxonomy of norms, which builds upon and merges previous taxonomies, to distinguish between different types of norms and enforcement mechanisms. We then provide a conceptual framework that identifies reasons for the effects of norms. This framework is based on psychological theories, which serve as a foundation for much of the empirical economic literature measuring norm effects. Finally, we present an overview of empirical economic papers that study the effects of norms on environmentally relevant behavior, as a particularly relevant area for the study of norms. The aim of this overview is to highlight which effects have been insufficiently studied and to give a sense of the potential of norms. This can help policy makers intervene in a more targeted way to address environmental problems.
