Social norms play an important role in individual decision making. We argue that two different expectations influence our choice to obey a norm: what we expect others to do (empirical expectations) and what we believe others think we ought to do (normative expectations). Little is known about the relative importance of these two types of expectation in individuals' decisions, an issue that is particularly important when normative and empirical expectations are in conflict (e.g., systemic corruption, high crime cities). In this paper, we report data from Dictator game experiments where we exogenously manipulate dictators' expectations in the direction of either selfishness or fairness. When normative and empirical expectations are in conflict, we find that empirical expectations about other dictators' choices significantly predict a dictator's own choice. However, dictators' expectations regarding what other dictators think ought to be done do not have a significant impact on their decisions after controlling for empirical expectations. Our findings about the crucial influence of empirical expectations are important for designing institutions or policies aimed at discouraging undesirable behavior.