Biological cell membranes regulate the transfer of matter and information between the intracellular and extracellular compartments as basic survival and maintenance functions for an organism. This volume contains a series of reviews that are c- cerned with how epithelial plasma membranes regulate the transport of solutes between the intracellular and extracellular compartments of a cell. This book is also an attempt to analyze the molecular basis for the movement of various solutes across an epithelial cell membrane. This volume is devoted to a diversity of epithelial transport mechanisms in rep- sentative cell membranes of a variety of living things. The first section of the book (Chapters 1–6) focuses on mechanisms of solute transport in epithelia of inver- brates. The last section which comprises ten chapters (Chapters 7–16) deals with solute transporters in epithelial cell membranes of vertebrates. It is hoped that with this particular ordering the reader can glean a telescopic view of the evolutionary history of the various epithelial solute transporters.