A basic assumption about natural hazard policy is risk information will influence risk perception, which will in turn affect individual behavior. This paper tests this basic assumption in the context of the National Flood Insurance Program and flood insur- ance purchasing in San Francisco Bay, California. Using spatially explicit household survey data, we use mediation models to analyze how an individuals knowledge about in which flood zone they live is associated with their flood risk perception and likeli- hood of purchasing flood insurance. The results suggest that the relationship between risk information, perception and behavior depends on whether the individual is aware of what flood zone they live in. Such risk-informed individuals will decrease their risk perception and insurance behavior if they know they are in a low-risk flood zone. In contrast, risk-uninformed individuals who are unsure of their flood zone are more likely to perceive higher risk and purchase insurance. The findings highlight the im- portance of ensuring that flood risk maps accurately reflect flood risks in the face of fine-scale topographic variation, the dynamics of urban structure, and climate change.