Since the late 19th century, X-ray structural studies have forged ahead through technological progress and the creative ingenuity of researchers. As high intensity X-ray sources and increased speed and sensitivity of the detectors have emerged, it's now possible to image the atomic structure of complex bio-macromolecules, the orbital electron density of small molecules, and to even follow the dynamical behavior of bio-macromolecules. Textbooks from which junior researchers can grasp the current art have not kept pace with the technological developments and diversification of the field. X-ray studies of bio-macromolecules require a broad understanding of the theory and practical methodologies. A project can include isolating, crystalizing, and adjudicating suitable samples, obtaining and analysing the X-ray data, and finally publishing the results in a standard format. Early decisions in a project can become pitfalls that swallow the unwary. It is increasingly essential to become adept at managing both proteins and nucleic acids. Whereas software is available to help in the critical problem of resolving the phase, expedience often encourages treating such tools as a black-box. The aim here is to help navigate the researcher through these multifarious issues. The book is intended to serve as a "companion" to experimentalists. It is divided into a general overview of X-ray structural analysis techniques (chapters 1-2) and a detailed discussion (chapters 3-16) that begins with the preparation of proteins and (uniquely) nucleic acids and ends with publishing the results and is organized to lead the reader through the whole process.