Eosinophilic esophagitis (EE) is rapidly emerging as a distinct disease entity in both pediatric and adult gastroenterology. The typical clinical presentation includes solid food dysphagia in young men who have an atopic predisposition. Food impaction necessitating endoscopic intervention is common. EE should be suspected, in particular, in patients with unexplained dysphagia or those with no response to antacid or anti-acid secretory therapy. Careful endoscopic and radiographic examinations reveal furrows, corrugations, rings, whitish plaques, fragile crêpe paper-like appearance, and a small-caliber esophagus. Mucosal erosion in the distal esophagus, characteristic to reflux esophagitis, is absent in EE. Marked eosinophil infiltration in the esophageal epithelia (>20 eosinophils per high-power field) is the diagnostic hallmark. Food antigens and aeroallergens may play a role in the pathogenesis of EE. The mechanisms may be dependent or independent of immunoglobulin E. Elimination diets, systemic and topical corticosteroids, leukotriene receptor antagonists, and, most recently, an anti-interleukin-5 monoclonal antibody have been used to treat EE. EE likely represents another example of eosinophil-associated inflammation of epithelia at the interface between external and internal milieu, similar to bronchial asthma and atopic dermatitis. This review summarizes recent progress in the diagnosis and management of EE and discusses future research directions.