To determine the cost of an emergency medical services (EMS) system, researchers, policymakers, and EMS providers need a framework with which to identify the components of the system that must be included in any cost calculations. Such a framework will allow for cost comparisons across studies, communities, and interventions. The objective of this article is to present an EMS cost framework. This framework was developed by a consensus panel after analysis of existing peer-reviewed and non-peer-reviewed resources, as well as independent expert input. The components of the framework include administrative overhead, bystander response, communications, equipment, human resources, information systems, medical oversight, physical plant, training, and vehicles. There is no hierarchical rank to these components; they are all necessary. Within each component, there are subcomponents that must be considered. This framework can be used to standardize the calculation of EMS system costs to a community. Standardizing the calculation of EMS cost will allow for comparisons of costs between studies, communities, and interventions.