A number of seismologists are pursuing the possibility of making scientifically credible earthquake forecasts or predictions. Others, however, are concerned about how the public might react to such forecasts [National Research Council, 1978; Geller, 1997]. In the 1920s, the president of the Seismological Society of America publicly predicted that southern California would suffer a severe earthquake within the next ten years. Only passing mention has been given to this episode in historical discussions of earthquake seismology [Richter, 1958, p. 388; Meltsner, 1979, pp. 343, 346–347]. Three related points are illustrated by this episode which may have some application to other instances of earthquake forecasting. Even credible predictions can evoke opposition from groups who see their economic interests threatened; predictions about future events may be undermined as scientific data are revised; and actual moderate earthquakes often spur more people to take hazard mitigation efforts than predictions of large earthquakes in the future.