Luminescent materials doped with rare earth ions (REI) are of great importance to science and technology. Modern solid-state optical technology is mainly based on rare earth ions doped materials, with applications ranging from solid-state lasers are used for industry, medicine and environmental monitoring, to active optical fibers for telecommunication purposes and phosphorous for cathode ray tube displays, plasma monitors and lightning applications. Rare-earth doped compounds have been widely used in tri-phosphor fluorescent lamps, 10-ray intensifying screens and newly developed vacuum mercury-free lamps. Recently, breakthroughs in inorganic light emitting diodes (LEDs) technology are significantly catalyzing the development of energy-efficient solid-state lighting (SSL) with long lifetime. This books discuss about the structural, Morphological and Photoluminescence Properties of Sm3 +, Eu3 +, Dy3 + and Dy3 + / Eu3 + ions Doped LaAlO3 Nanophosphors synthesized by Hydrothermal Method for White Light Emitting Diodes Applications.