Challenges in characterizing symptom heterogeneity and identifying active EoE in patients include an inability to verbalize their symptoms (e.g., patients are too young) or developed behavioral coping adaptations (e.g., chewing more slowly, lubricating foods with sauces). The EndoFLIP (Endolumenal Functional Imaging Probe) is a tool to characterize esophageal distensibility (the amount of stretch in the esophagus) at the time of endoscopy. A catheter with a balloon is inserted into the esophagus, while sensors measure the diameter and amount of pressure as the balloon is inflated. We previously showed that patients with active disease have decreased distensibility compared to those in remission. We plan on establishing the pediatric normal values for esophageal distensibility and correlating with patient symptoms and microscopic tissue evaluation. This tool also gives us the ability to determine physiological improvement while testing novel therapeutics.