In this reviw the scope of modern applications of polymers as electronic materials is noted and the status of theoretical models of their electrical properties is indicated. Emphasis is placed on the role of disorder in localizing injected charges and excitons. Because of the rudimentary state of the quantitative characterization of the structure of polymer films, direct measurements (e.g., via valence electron photoemission spectroscopy) of the energy distributions of localized charges are utilized to characterize the effects of composition and processing on electrical properties as well as to test theoretical models. The triboelectric charging of polymers is examined as an illustration of the application of current models to describe a subtle electrical phenomenon of practical interest in electrophotography and the fabrication of microelectronic devices.