In the first half of the twentieth century, when seismology was in its infancy, renowned geologist Bailey Willis faced off with fellow high-profile scientist Robert T. Hill over a question with life-or-death consequences for the millions of people migrating west. Is Southern California earthquake country? Susan Hough's entwined biographies of Hill and Willis offer a lively, accessible account of how politics and financial interests influenced the development of earthquake science. During this period of debate, severe quakes in Santa Barbara (1925) and Long Beach (1933) caused scores of deaths and significant damage, becoming turning points for scientific knowledge and mainstreaming the idea of earthquake safety. The Great Quake Debate sheds light on enduring questions about the environmental hazards of our dynamic planet. What challenges confront scientists who bear bad news in the public arena? How do we balance risk and the need to sustain communities and cities? And how well has California come to grips with its geological inheritance?