The powder diffraction experiment is the cornerstone of a truly fundamental materials characterization technique—diffraction analysis—and it has been used for many decades with exceptional success to provide accurate information about the structure of materials. Although powder data usually lack the three-dimensionality of a diffraction image, the fundamental nature of the method is easily appreciated from the fact that each powder diffraction pattern represents a one-dimensional projection of the three-dimensional reciprocal lattice of a crystal. The quality of the powder diffraction pattern is usually limited by the nature and energy of the available radiation, the resolution of the instrument, and the physical and chemical conditions of the specimen. Since many materials can only be prepared in a polycrystalline form, the powder diffraction experiment becomes the only realistic option for a reliable determination of the crystal structure of such materials. Considering all of the above, this chapter discusses powder diffraction instrumentation, focusing on goniometer design, X-ray beam conditioning methods—such as collimation and monochromatization—and detectors, the devices used for registering the diffracted beam. It concludes with a brief overview of non-ambient techniques, including variable-temperature and variable-pressure attachments, as well as facilities for performing experiments under magnetic and other applied fields.