Blue electroluminescent (EL) devices were fabricated with Si nanocrystals produced by ultrasonic fracturing of porous silicon (PSi) as well as silicon and germanium nanocrystals synthesized through a control chemical reaction. The active EL material consists of Si and Ge nanocrystals embedded in various host matrices such as polyvinylcarbazole (PVK), polymethylmethacrylate (PMMA), silica sol-gels and other organic polymers and small organic molecules. Several device configurations were used to induce EL processes that rely on radiative electron-hole recombination within the nanocrystals. We report on the optical and electrical properties of these devices. Applications for these EL devices include highly efficient light emitting devices. The cost and ease of processing of these material systems make them potentially ideal for flat panel display applications.