Advances have been made in understanding specialized aspects of acquired mucosal immunity and the importance of cross-talk between host innate and acquired immune responses in host mucosal defense. These advances include elucidation of a molecular basis for the coordinated trafficking and retention of lymphocytes in intestinal sites, new insights into the possible extrathymic origin of mucosal T cells in the intestine, and the description of ligands that may be the targets of intraepithelial T-cell recognition. The past year has witnessed the characterization of an array of regulated epithelial cell mediators and responses important for host mucosal defense against enteric microbial pathogens and firmly establishes epithelial cells as an integral component of the mucosal immune network. Animal models continued to further understanding of intestinal inflammatory disease, and studies on tissue transglutaminase have generated significant new insights into the immunopathogenesis of human celiac disease.