"Improved Seismic Monitoring - Improved Decision-Making" describes and assesses the varied economic benefits potentially derived from modernizing and expanding seismic monitoring activities in the United States. These benefits include more effective loss avoidance regulations and strategies, improved understanding of earthquake processes, better engineering design, more effective hazard mitigation strategies, and improved emergency response and recovery. The economic principles that must be applied to determine potential benefits are reviewed and the report concludes that although there is insufficient information available at present to fully quantify all the potential benefits, the annual dollar costs for improved seismic monitoring are in the tens of millions and the potential annual dollar benefits are in the hundreds of millions.