Ceramics and glass-ceramics are principally known in industry for their good electrical insulation properties. However, some glass-ceramics exhibit other unusual electrical characteristics. The suitability of the various routes for producing glass-ceramics with specific properties for particular applications are discussed. These include piezoelectric and pyroelectric materials, high-dielectric-constant materials for use in capacitors, materials whose dielectric constant varies with temperature, electro-optic materials, and superconductors.