In social psychology there have been different opinions about the predictive power of social norms. Some authors argue that they are crucial for the full comprehension of human behavior. Others, however, claim that this concept is too elusive and difficult to test empirically. The literature on this research topic has recently pointed out how different kinds of social normative influence can have a more or less important role, depending on which behavior is analyzed. Specifically, the present review will focus on pro-environmental behaviors, taking into account the main models and types of normative influence emerging from social-psychological and environmental-psychological research.