Summary Mortality for infants is almost 2 times higher and for children 2.6 times higher in rural communities compared with urban settings; little is known about what portion of these children interact with the Emergency Medical Services (EMS) system. Data for rural health disparities currently come from vital statistics and suggest that much of the excess rural mortality occurs in conditions that are common reasons for Emergency Medical Services (EMS) dispatch. EMS providers provide scene response, resuscitation, stabilization, and transport for a range of life-threatening conditions and the care they deliver is a critical link in the chain of survival. Our research on EMS care in urban areas finds that more than half of out of hospital children's emergencies have an adverse safety event (ASE) during the delivery of care, and the highest rates are seen in children with cardiopulmonary arrest, trauma, respiratory distress, seizures, and births. Currently, it is not known if and to what extent potentially modifiable factors occurring during EMS care contribute to disparities in mortality. This project proposes to address this knowledge gap through the following aims: Aim 1: Conduct a comprehensive comparative investigation into the epidemiology of disparities in rural child outcomes from life-threatening emergencies to identify factors associated with improved outcomes & survival; Aim 2: Identify and characterize ASEs that occur during EMS care and understand how modifiable and nonmodifiable factors magnify or attenuate the effect of ASEs on outcomes; Aim 3: Test a new linear approach to cognitive aids to reduce errors and promote high-quality EMS resuscitation for children. This research will be a substantive departure from the status quo by leveraging big data approaches to move beyond high level outcome frequencies and get to the source of what might be preventable through the health care delivery system. Errors are considered an important source of preventable harm and potentially death. Completion of this project will result in: (i) a novel population-based epistry on child mortality and morbidity and EMS response in rural and urban settings; (ii) a conceptual framework of how errors contribute to preventable morbidity and mortality for rural and urban children; and (iii) pilot data on the effectiveness of linear cognitive aids to improve the safety of EMS care and potentially reduce disparities in rural and urban child morbidity and mortality.