Study objective: To determine whether the receipt of more than or equal to 30 mL/kg of intravenous fluid in the first hour after emergency department (ED) arrival is associated with sepsis-attributable mortality among children with hypotensive septic shock. Methods: This is a retrospective cohort study set in 57 EDs in the Improving Pediatric Sepsis Outcomes quality improvement collaborative. Patients less than 18 years of age with hypotensive septic shock who received their first intravenous fluid bolus within 1 hour of arrival at the ED were propensity-score matched for probability of receiving more than or equal to 30 mL/kg in the first hour. Sepsis-attributable mortality was compared. We secondarily evaluated the association between the first-hour fluid volume and sepsis-attributable mortality in all children with suspected sepsis in the first hour after arrival at the ED, regardless of blood pressure. Results: Of the 1,982 subjects who had hypotensive septic shock and received a first fluid bolus within 1 hour of arrival at the ED, 1,204 subjects were propensity matched. In the matched patients receiving more than or equal to 30 mL/kg of fluid, 26 (4.3%) of 602 subjects had 30-day sepsis-attributable mortality compared with 25 (4.2%) of 602 receiving less than 30 mL/kg (odds ratio 1.04, 95% confidence interval 0.59 to 1.83). Among the patients with suspected sepsis regardless of blood pressure, 30-day sepsis-attributable mortality was 3.0% in those receiving more than or equal to 30 mL/kg versus 2.0% in those receiving less than 30 ml/kg (odds ratio 1.52, 95% confidence interval 0.95 to 2.44.) Conclusion: In children with hypotensive septic shock receiving a timely first fluid bolus within the first hour of ED care, receiving more than or equal to 30 mL/kg of bolus intravenous fluids in the first hour after arrival at the ED was not associated with mortality compared with receiving less than 30 mL/kg.