: media-1vid110.1542/5972296744001PEDS-VA_2018-1056 OBJECTIVES: To characterize and compare ambulatory antibiotic prescribing for children in US pediatric and nonpediatric emergency departments (EDs). A cross-sectional retrospective study of patients aged 0 to 17 years discharged from EDs in the United States was conducted by using the 2009-2014 National Hospital Ambulatory Medical Care Survey ED data. We estimated the proportion of ED visits resulting in antibiotic prescriptions, stratified by antibiotic spectrum, class, diagnosis, and ED type ("pediatric" defined as >75% of visits by patients aged 0-17 years, versus "nonpediatric"). Multivariable logistic regression was used to determine factors independently associated with first-line, guideline-concordant prescribing for acute otitis media, pharyngitis, and sinusitis. In 2009-2014, of the 29 million mean annual ED visits by children, 14% (95% confidence interval CI: 10%-20%) occurred at pediatric EDs. Antibiotics overall were prescribed more frequently in nonpediatric than pediatric ED visits (24% vs 20%, < .01). Antibiotic prescribing frequencies were stable over time. Of all antibiotics prescribed, 44% (95% CI: 42%-45%) were broad spectrum, and 32% (95% CI: 30%-34%, 2.1 million per year) were generally not indicated. Compared with pediatric EDs, nonpediatric EDs had a higher frequency of prescribing macrolides (18% vs 8%, < .0001) and a lower frequency of first-line, guideline-concordant prescribing for the respiratory conditions studied (77% vs 87%, < .001). Children are prescribed almost 7 million antibiotic prescriptions in EDs annually, primarily in nonpediatric EDs. Pediatric antibiotic stewardship efforts should expand to nonpediatric EDs nationwide, particularly regarding avoidance of antibiotic prescribing for conditions for which antibiotics are not indicated, reducing macrolide prescriptions, and increasing first-line, guideline-concordant prescribing.