Each year, approximately 300,000 people in the United States suffer a cardiac arrest while going about their daily lives. Known as an out-of-hospital cardiac arrest (OHCA) in the medical community, survival rates have hovered around 8 percent for the last 30 years and can vary greatly between communities. When a group of health leaders in Atlanta considered the possibility of installing automatic defibrillators (AEDs) throughout the city to help improve survival rates in 2003, they quickly recognized that their inability to track the progress of OHCA patient outcomes through the medical system — from the ambulance to the hospital to the moment of discharge — would make it impossible to assess the effectiveness of such an investment. This case study tells the story of how Dr. Bryan McNally, Associate Professor of Emergency Medicine at Emory University, worked with Atlanta hospitals, emergency medical technicians, medical software providers, a network of medical experts, and Atlanta’s Center for Disease Control and Prevention to develop, design, and implement the Cardiac Arrest Registry to Enhance Survival (CARES), the first database that tracks key details for OHCAs.