The aim of this study was to examine differences between general and pediatric emergency departments (PEDs) in adherence to the American Academy of Pediatrics bronchiolitis management guidelines. We conducted a nationally representative study of ED visits by infants younger than 24 months with bronchiolitis from 2002 to 2011 using the National Hospital Ambulatory Medical Care Survey. Diagnostic testing (complete blood counts, radiographs) and medication use (albuterol, corticosteroids, antibiotics and intravenous fluids) in general emergency departments (GEDs) were compared with those in PEDs before and after 2006 American Academy of Pediatrics guideline publication. Weighted percentages were compared, and logistic regression evaluated the association between ED type and resource use. Of more than 2.5 million ED visits for bronchiolitis from 2002 to 2011, 77.3% occurred in GEDs. General emergency departments were more likely to use radiography (62.7% vs 42.1%; adjusted odds ratio [aOR], 2.4; 95% confidence interval [CI], 1.4-4.1), antibiotics (41.3% vs 18.8%; aOR, 2.8; 95% CI, 1.5-5.2), and corticosteroids (24.3% vs 12.5%; aOR, 2.1; 95% CI, 1.0-4.5) compared with PEDs. Compared with preguideline, after guideline publication PEDs had a greater decrease in radiography use (-19.7%; 95% CI, -39.3% to -0.03%) compared with GEDs (-12.2%; 95% CI, -22.3% to -2.1%), and PEDs showed a significant decline in corticosteroid use (-12.4%; 95% CI, -22.1% to -2.8%), whereas GEDs showed no significant decline (-4.6%; 95% CI, -13.5% to 4.3%). The majority of ED visits for bronchiolitis in the United States occurred in GEDs, yet GEDs had increased use of radiography, corticosteroids, and antibiotics and did not show substantial declines with national guideline publication. Given that national guidelines discourage the use of such tests and treatments in the management of bronchiolitis, efforts are required to decrease ED use of these resources in infants with bronchiolitis, particularly in GEDs.