Corruption marks a major societal challenge. Although many corrupt practices such as bribery are outlawed in national codes of laws, stark differences in (perceived) corruption levels persist around the world. To explain this gap between legal norms and actual behavior, the current corruption literature emphasizes the importance of social norms, the unwritten rules that guide behavior. Recent lab research suggests that short social norms messages can reduce people’s perceptions of descriptive norms about bribery and lower their own inclination to bribe. In pursuit of first field evidence for this link, we conducted a pre-registered lab-in-the-field study in South Africa. Throughout town we distributed posters that contained a descriptive norms messages about bribery. Inside a mobile, we used an incentivized assessment of social norms (descriptive and injunctive) and a behavioral bribery task. Outside the lab, we assessed the missing stock in a local pharmacy as a real-life measure of corruption. Our results reveal that only during the period in which the poster was put up, participants’ perceived descriptive norms of bribery, and their own willingness to engage in bribery decreased. We discuss the findings in light of their relevance for the interdisciplinary literature dealing with social norms and (anti-) corruption.