Boron nitride can be excited to luminesce by (1) alternating electric fields, (2) ultraviolet photons, or (3) cathode rays. The luminescence, in all cases, has a complex emission spectrum, extending from approximately 2950 A to 6500 A. The relative intensities of the bands in the fine structure are affected by current density with cathode-ray excitation, and by the energy (frequency) of the photons with ultraviolet excitation. The maximum of the photoluminescence emission intensity with temperature occurs at about 875°K, with the luminescence emission intensity falling to 50% of the maximum value at approximately 1375°K. Correspondence of known infrared absorption bands with energy differences in the fine structure in the luminescence suggest vibrational origins for the fine structure. The identities of the excited electronic states have not yet been ascertained, although these may be due to exciton states, impurity states, or surface states.