Eosinophilic Esophagitis is an antigen mediated chronic disease that is distinct from gastroesophageal reflux disease. EoE an emerging clinical problem that is rapidly growing in incidence and in recognition. It is characterized clinically by feeding dysfunction, dysphagia and reflux-like symptoms. Histologically EoE is identifiable by a dense epithelial eosinophilic infiltrate. Experimental modeling and clinical studies over the last decade have greatly improved our understanding of this disease and led to improvements in clinical understanding and the assessment of therapeutic options for patients and their clinicians who manage this disease. In this review we review the cliniopathologic diagnostic criteria and our understanding of EoE as an allergic disease with genetic and immunological components in the pathophysiology. We make note of the berth of studies defining the importance of the epithelial barrier and discuss the concept of barrier function as an initiating or perpetuating factor for this disease. The relationship between the symptoms of dysphagia, feeding dysfunction and our current knowledge of the underlying pathophysiologic mechanisms of these clinical indicators, as well as advances in clinical assessment of decreased esophageal distensibility and narrowing in EoE patients. Lastly, therapeutic implications relating to the advances that have led to our current understanding of the pathophysiology of EoE are explored.