Eosinophilic gastrointestinal disorders (EGIDs) are a collection of disorders characterized by allergy-driven inflammation of the gastrointestinal (GI) tract. Affected patients typically present with nonspecific symptoms of GI dysfunction and are frequently found to have mucosal abnormalities during endoscopy as well as increased eosinophil levels on tissue biopsy that are felt to be responsible for generating the clinical findings. Each of these findings is important in both the diagnosis and management of EGIDs. Understanding the impact of histopathologic and endoscopic changes on clinical signs and symptoms is critical to developing an understanding of the natural history of these disorders as well as to the generation of validated assessment tools and targeted therapies. We explore these relationships in this review.