A survey of the middle and vacuum ultraviolet spectroscopy of the upper atmosphere. The various physical and chemical processes involved in the interaction of radiation with the atoms and molecules of the upper atmosphere are reviewed, and the ultraviolet spectral features that result from these processes are summarized. Various ways are discussed in which rocket and satellite observations of these spectral features can be used to study the composition of the upper atmosphere. These include observations of the absorption of radiation by the upper atmosphere, observations of the scattering of solar radiation by the upper atmosphere, and observations of the emission of ultraviolet radiation from the upper atmosphere. (See also RM-4392.) 54 pp.