This study investigates how ownership and/or management affects ambulance services across the United States. We investigate whether ambulance quality, measured by patient transportation time, varies by organization type. We estimate the effect of ownership structure on response time variables using data from the National EMS Information System (NEMSIS) for the years 2010–2015, the most comprehensive data set on emergency medical services. Focusing on ground transportation (as opposed to air and water transportation) and on Medicare-eligible (age 65 years and older) patients, we find that, on average, ambulance services owned by fire departments respond faster than those managed by other types of ownership. Specifically, fire-department-owned medical emergency services located in urban areas are approximately 12 percent or six minutes faster than those owned by community nonprofit organizations, and are around five minutes faster than those owned by government agencies. Using some admittedly crude measures of costs, we find no evidence of significant cost differences by ownership structure. Based on evidence from other sources,we find some weak evidence that private-sector ambulances are better than other types of ambulances at collecting payment from patients, private-sector insurance companies,Medicare,and Medicaid. In the end, the strongest conclusion is that few reliable data are available to guide local governments that are trying to decide how to structure emergency services in their region