This study examines the perceived risks and mitigating behavior of Maine households who received new information on their exposures to significant health risks from indoor radon. The observed responses of these households illustrate conceptual issues related to designing an effective risk information program. Despite the involvement of generally well-motivated homeowners and well-intentioned researchers and government officials, we conclude that the risk information approach used in Maine failed to induce appropriate, cost-effective voluntary protection. The results indicate that, after receiving radon test results, information on associated health risks, and suggestions on how to reduce exposures: perceived risks tended to understate objective risks by orders of magnitude, and there was no statistically significant relationship between mitigating behavior and objective risks. These results suggest that the formation of risk perceptions and subsequent behavioral adjustments involve complex interactions among information, contextual, socioeconomic, and psychological variables. Therefore, government programs that seek to reduce health and safety risks with information programs, instead of using more conventional enforced standards, must be crafted very carefully to accommodate this complex process.