The interactions between pathogenic bacteria and their hosts are dynamic and multifaceted. The presence of bacterial pathogens at mucosal surfaces triggers a. vigorous inflammatory response that is essential for controlling the replication and spread of the intruder. However, inflammation also damages host tissue, and thus its induction must be tightly regulated. The molecular mechanisms underlying the stimulation of an inflammatory response by pathogenic bacteria have been elusive. The urinary tract infection (UTI) model system has been a powerful tool for understanding the interactions between cells of the innate host defense system, as well as the bacterial factors and host receptors involved in eliciting host cell activation. This article will discuss several recent findings that enhance our understanding of inflammatory effector mechanisms and pathogen recognition in the context of a mucosal surface.