A review of the role of dielectrics in the performance of ZnS:Mn-based alternating-current thin-film electroluminescent (ACTFEL) devices is given. The most important factors, including charge storage capacity, relative permittivity, breakdown strength, stability, barrier properties, and the tendency of interaction with adjacent layers have been taken into account by way of defining successful candidates for each individual dielectric layer in the structure. Particular emphasis is placed on such preparation conditions as the substrate temperature, growth rate, and post-deposition annealing. The nature of various degradation modes a affecting the dielectric properties is extensively discussed. The role of the insulator-semiconductor interface (ISI) and the importance of the proper choice of cladding dielectrics is stressed in order to achieve high efficiency and stability of the device.