The task of the mucosal immune system guarding the gastrointestinal tract is immense. This system must be able to recognize and eliminate pathogens that enter the gastrointestinal tract without harming other functions. To achieve this, the mucosal immune system must be able to distinguish between potentially harmful and beneficial or commensal bacteria as well as a wide variety of potential dietary antigens. To coordinate this undertaking, there is considerable communication between the cells of the intestinal epithelium and underlying cells of the immune system. Further, there is communication between host cells and pathogens that seek to breech the intestinal mucosa. On detection of such pathogens, the intestinal epithelium coordinates a complex mucosal inflammatory response designed to eliminate all potentially dangerous foreign entities. Although much of this bacteria-epithelialimmune cell crosstalk maintains the well-being of the intestinal mucosa, some pathogens have found ways to exploit mucosal immune responses to their own benefit. It is also possible that inappropriate activation of the mucosal immune system can lead to chronic inflammatory disease states. Thus, understanding bacterial-epithelial-immune cell interactions may likely contribute to understanding both bacterial pathogenesis and chronic inflammatory disease in the intestine. This review highlights progress made within the past year toward understanding these cellular interactions.