A synthesis is presented of the social psychological process that explains how members of the public receive, process, and eventually come to take protective actions in response to the receipt of warnings of extreme floods. The case is made that effective public warnings must provide for public interaction and foster the search for information in addition to received warnings. Several specific recommendations for future research are presented. In fact the communication of climatological, geological and technological hazards, risk, and disaster information and warnings to the public is an almost continual process when viewed globally. For example, it has been estimated that an evacuation a day occurs on average in the United States alone. Warnings are issued for varied risks, for example, hurricanes, floods, volcanic eruptions, earthquakes, and transported or stored hazardous materials. Hazards such as these vary in character, but they are similar in that they can result in low- probability / high-consequence disaster events, and because the basic social psychological process that directs public response is similar across hazards. It is the purpose of this paper to synthesize research and knowledge on the process that underlies public response to warnings of disasters.