It is essential for the survival of cells to maintain their volume within certain limits: Profound alterations interfere with the integrity of the cell membrane and the cytoskeletal architecture. Cells use various methods to adjust osmotic pressure gradients which in turn govern water movement across cell membranes. The most rapid and efficient means is ion transport across the cell membrane. However, to avoid excessive alterations of intracellular ion concentration, cells additionally employ organic osmolytes for osmoregulation and modify their metabolism, thus generating or disposing osmotically active organic substances. But a given cell uses only part of the cell volume regulatory mechanisms at their disposal: The large repertoire available allows for a selection of those which have the least untoward impact on cell function. The present book is a collection of reviews on the various aspects of cell volume regulation, written by internationally leading experts, and constitutes a valuable addition to the library of those working in the field.