The treatment and analysis of small-angle X-ray scattering data are reviewed with specific concern for the glass science. The studies detail the characterization of the submicroscopic structure existing in terms of two-phase particulate systems, multiphase particle systems, non-particulate systems, including those of fractal surfaces, and the application of small-angle X-ray scattering to the examination of the intermediate-range order of glasses. The methods developed are illustrated by small-angle X-ray scattering and anomalous small-angle X-ray scattering results obtained from optical filter glass, glass produced by the sol–gel technique, optical colorless glass inclining to opalescence, porous glass and single-phase phosphate glass.