Background and Objectives Pediatric headaches, including migraine, are a common reason for emergency department (ED) presentation. IV valproic acid (VPA) followed by oral VPA tapers are often used to abort pediatric headache and reduce recurrence, though limited data exist regarding this approach. This study evaluated the effectiveness of IV VPA and oral VPA tapers for the treatment of acute pediatric headaches in the ED in preventing return encounters. Methods This is a retrospective cohort study of patients aged 5–21 years presenting to a tertiary-care pediatric ED from 2010 to 2016 who received IV VPA for headache or migraine. Primary outcomes were ED disposition, percent pain reduction (initial vs 2-hour patient-reported pain score [10-point scale]), and return for acute headache treatment within 1 month. Results A total of 486 ED encounters were included with a median patient age of 15 years; most of them were females (76%, 369/486). Of available pain scores within 2 hours of IV V