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, Dr. Jan Drenth, recognized internationally for his numerous contributions to crystallographic research, provides an up-to-date and technically rigorous introduction to the subject. Principles of Protein X-ray Crystallography provides the theoretical background necessary to understand how the structure of proteins is determined at atomic resolution. The book is an introduction for graduate students, postdoctoral researchers, and established scientists who want to use protein crystallography in their own endeavors, or need to understand the subject in order to critically evaluate the literature. 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.