Celiac disease is a common and lifelong food intolerance, affecting approximately 1% of the population. Because of a mechanism not completely understood, the ingestion of wheat gluten, and of homologue proteins of barley and rye, induces in genetically predisposed individuals pronounced inflammatory reactions mainly at the site of small intestine. Gluten, the triggering factor, is a complex protein mixture highly resistant to the gastrointestinal enzymatic proteolysis, and this results in the presence of large, and potentially immunogenic, peptides at the intestinal mucosa surface. During the last decade, several studies have defined gluten peptides able to stimulate adaptive T cells, of either CD4 or CD8 phenotype, and to activate innate (non T) immune cells. This review examines the complete repertoire of gluten peptides recognized by celiac T cells and discusses the several translational implications that the identification of these epitopes opens.