Tight junction proteins connect epithelial and endothelial cells and, importantly, form selective barriers and channels for paracellular transportation. Two types of tight junction proteins – the claudin family (claudins-1 to -27) and the TAMP family (occludin, Marvel-D2, and tricellulin) – can be distinguished molecularly and functionally. Recent work has focused on delineating the functional significance of differences in selective permeability, for example, by examining the regulatory mechanisms of tight junctions. This work is of great clinical importance as many inflammatory or infectious diseases are characterized by increased permeability and the manipulation of tight junctions presents a new horizon in the development of novel therapeutics. The volume Barriers and Channels Formed by Tight Junction Proteins II provides a detailed look at the recent advances in our understanding of tight junction regulation and dysregulation. The papers included focus on three major themes: inflammation and gastrointestinal function; epithelial transport, barrier modulation, and food components; and tight junctions in intestinal and renal epithelia.