Environmental groups have become the chief antagonists toward agricultural biotechnology innovations. They demonstrate and disseminate private information with the objective of changing the behavior of consumers and producers. We use experimental auctions with adult U.S. consumers and show that this information reduces significantly the demand for genetically modified (GM)-food products and that it has significant public good value—an average of 3 cents per product purchased, or roughly $2 billion annually. We also show that the dissemination of independent third-party information about agricultural biotechnology dissipates most of the public good value of negative GM-product information.