The biological impact of the NF-kappaB transcriptional system in various intestinal biological processes such as cellular proliferation, differentiation and survival, inflammation, and carcinogenesis is a relatively young field of research. Less than a decade ago, reviews addressing NF-kappaB regulation and function in the intestine had to borrow concepts and hypotheses from other bodily systems such as the joints (rheumatoid arthritis), the lungs (asthma), or the cardiovascular system (systemic inflammatory states, sepsis). Since then, important progress has been made in defining the various functional aspects of NF-kappaB signaling in intestinal homeostasis and diseases, and exciting new paradigms have emerged from this research. This review will discuss the function of NF-kappaB in intestinal homeostasis and diseases in relation to injury responses and microbial colonization/infection.