Cell-cell junctions are multi-molecular complexes that link neighboring cells. They help maintain tissue integrity, act as barriers to permeability, and allow intercellular transport. They also reinforce cell polarity by separating the apical and basolateral domains of the plasma membrane. Written and edited by experts in the field, thiscollection from Cold Spring Harbor Perspectives in Biology includes contributions covering each of the main junction types--tight junctions, adherens junctions, and desmosomes--as well as the more specialized junctions of neuronal and immune cells. The contributors examine the assembly and structure of different cell junctions, their roles in cellular signal transduction, and their importance during development and normal tissue homeostasis. Including discussion of the roles of junctions in various diseases, the volume is a vital reference for cell and developmental biologists wishing to know how cells interact in multicellular organisms.