The Great Southern California ShakeOut program in November 2008 was the largest earthquake drill in U.S. history, involving more than 5 million southern Californians through a broad-based outreach program, media partnerships, and public advocacy by hundreds of partners. The basis of the drill was a scenario for a magnitude 7.8 earthquake on the southern San Andreas fault, which would cause broad devastation. The scenario was developed with the contributions of over 300 scientists, engineers, and other experts. In early 2009, the decision was made to hold the drill statewide on the third Thursday of October each year. A summary of the 2008 and 2009 drills will be shared in this session and plans for other ShakeOut drills elsewhere. A key aspect of the ShakeOut is the integration of a comprehensive earthquake scenario (incorporating earth science, engineering, policy, economics, public health, and other disciplines) and the lessons learned from decades of social science research about why people get prepared. The result is a “teachable moment” on par with having an actual earthquake (often followed by increased interest in getting ready for earthquakes). ShakeOut creates the sense of urgency that is needed for people, organizations, and communities to get prepared, to practice what to do to be safe, and to learn what plans need to be improved.