We explore the idea that prosocial behavior in experimental games is driven by social norms imported into the laboratory. Under this view, differences in behavior across subjects is driven by heterogeneity in sensitivity to social norms. We introduce an incentivized method of eliciting individual norm-sensitivity, and we show how it relates to play in public goods, trust, dictator and ultimatum games. We show how our observations can be rationalized in a stylized model of norm-dependent preferences under reasonable assumptions about the nature of social norms. Then we directly elicit norms in these games to test the robustness of our interpretation.