Barrett esophagus is a preneoplastic condition defined by the presence of intestinal metaplasia (ie, goblet cells) in an endoscopically apparent columnar-lined esophagus. Dysplasia is the most important risk factor for cancer development among patients with Barrett esophagus; approximately 6% of patients with high-grade dysplasia progress to adenocarcinoma within 1 year. Surgical pathologists are generally expected to address 2 clinical concerns when evaluating mucosal biopsy samples from patients with suspected Barrett esophagus; they should note the presence, or absence, of goblet cells and comment on the grade of dysplasia when it is identified. Biopsy samples from patients with Barrett esophagus are categorized as negative for dysplasia, indefinite for dysplasia, or positive for dysplasia; in the latter situation, the severity of dysplasia is classified as low or high grade. Several histochemical stains, immunohistochemical stains, and molecular techniques can be used to facilitate detection of goblet cells and classify dysplasia in patients with Barrett esophagus, although their added value to routine morphologic assessment is not entirely clear. The purpose of this review is to discuss the state of the art regarding application of ancillary studies to esophageal samples from patients with a columnar-lined esophagus.