Calcium plays an important role in a wide variety of biological processes and is uniquely suited to act as a promoter or preventer of activities in biological systems. These two volumes provide the modern experimental techniques for studying calcium-binding proteins and their behaviour in vitro and in vivo. The primary emphasis is on protein chemistry and biophysical methods, and many of the methods described can also be used in the study of proteins that do not bind calcium. Volume I of this two-volume set provides information on the role of calcium in intracellular secondary messenger activation mechanisms. It also provides a wealth of information about protein purification strategies, X-ray crystallography and other studies focused on specific calcium-binding proteins. By introducing the various classes of intra- and extra-cellular calcium-binding proteins and their mode of action, this first volume sets the stage and provides the necessary background for volume II. The second volume provides a vast array of modern experimental techniques that can be used to study the solution structure, stability, dynamics, calcium-binding properties and biological activity of calcium-binding proteins in general. Together, these two volumes provide all that a researcher needs to conduct research on calcium-binding proteins.