This paper contributes to the growing literature on anti-corruption accountability by comparing individual decision making under different norms and institutions. Employing an experimental methodology, I examine how the propensity to report corruption differs between Northern and Southern Italians, two groups that experience very different levels of corruption in everyday life. Further, the experiment measures behavior under two different institutional environments: a "strict enforcement" condition where reports always result in sanctions against perpetrators, and a "lax enforcement" condition where 50% of reports are ignored. I find no difference in the behavior of Northern and Southern Italians in the lax enforcement condition, but in the strict enforcement condition, Southerners are much more likely to denounce wrongdoing, while the behavior of Northerners remains unchanged. These results demonstrate that exposure to corruption may strengthen accountability norms, but only in the presence of highquality enforcement institutions.