OBJECTIVES: With soaring US health care costs, identifying areas for reducing cost is prudent. Our objective was to identify the burden of potentially unnecessary pediatric emergency department (ED) transfers and factors associated with these transfers. METHODS: We performed a retrospective analysis of Pediatric Hospital Information Systems data. We performed a secondary analysis of all patients ≤19 years transferred to 46 Pediatric Hospital Information Systems-participating hospital EDs (January 1, 2013, to December 31, 2014). The primary outcome was the proportion of potentially unnecessary transfers from any ED to a participating ED. Necessary ED-to-ED transfers were defined a priori as transfers with the disposition of death or admission >24 hours or for patients who received sedation, advanced imaging, operating room, or critical care charges. RESULTS: Of 1 819 804 encounters, 1 698 882 were included. A total of 1 490 213 (87.7%) encounters met our definition for potentially unnecessary transfer. In multivariate analysis, age 1 to 4 years (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.34-1.39), female sex (OR, 1.08; 95% CI, 1.07-1.09), African American race (OR, 1.51; 95% CI, 1.49-1.53), urban residence (OR, 1.75; 95% CI, 1.71-1.78), and weekend transfer (OR, 1.06; 95% CI, 1.05-1.07) were positively associated with potentially unnecessary transfer. Non-Hispanic ethnicity (OR, 0.756; 95% CI, 0.76-0.78), nonminor severity (OR, 0.23; 95% CI, 0.23-0.24), and commercial insurance (OR, 0.86; 95% CI, 0.84-0.87) were negatively associated. CONCLUSIONS: There are disparities among pediatric ED-to-ED transfers; further research is needed to investigate the cause. Additional research is needed to evaluate how this knowledge could mitigate potentially unnecessary transfers, decrease resource consumption, and limit the burden of these transfers on patients and families.