The biology of membrane transport is a field which has undergone intensive development in the past twenty years. Until the early 1970's, studies were primarily restricted to the plasma membranes of a few model cells (e.g. red blood cells, squid giant axons) or tissues actively engaged in regulation of solute absorption by the organism (e.g. epithelia). The approach was primarily in terms of thermodynamics (characterization of those ions/solutes which are actively transported) or kinetics (analysis of the specificity of transport systems). Several major developments have revolutionized the field since those early days. First, Mitchell's Chemiosmotic Hypothesis, the acceptance of which in the 1970's brought the field classically known as "Bioenergetics" within the domain of membrane transport. Second, reconstitution techniques have enabled the transport properties of membrane proteins from a variety of membrane types to be studied in isolation from regulatory factors present in the living cell. This book should be of interest to advanced undergraduate and postgraduate students of biochemistry, cell biology, physiology and microbiology.