X-ray crystallography is an established method for studying the structure of proteins and other macromolecules. As the importance of proteins grows, researchers in many fields have found that a working knowledge of X-ray diffraction is an indispensable tool. In this new edition of his essential work, the internationally recognized researcher Dr. Jan Drenth offers an up-to-date and technically rigorous introduction to the subject, providing the theoretical background necessary to understand how the structure of proteins is determined at atomic resolution. New material in the 3rd edition includes a section on twinning, an additional chapter on crystal growth and a discussion of single-wavelength anomalous dispersion.