Shape-controlled luminescent oxide nanocrystals have been synthesized by a high temperature solution phase growth method. Thermal decomposition of metal precursors in the presence of trioctylphosphine oxide (TOPO), hexadecanediol, oleic acid, and benzyl ether resulted in highly crystalline, monodisperse oxide nanocrystals . This route provides crystalline nanoparticles with shapes of square plates or spheres dependent upon the growth variables, such as the choice of metal precursor and capping molecules. Upon evaporation of the hexane solvent, the plate-type Gd@sub 2@O@sub 3@ nanocrystals self-assembled into stacked plates lying on their edge. Alternatively, the reaction of Gd(acac)@sub 3@. with hexadecanediol resulted in spherical Gd@sub 2@O@sub 3@ nanocrystals with a diameter of 2 nm, showing that the type of metal precursors plays an important role in control of the shape of nanocrystals. The effects on the crystal growth of other reaction parameters, including reaction temperature and different combinations of organic solvents, will be discussed. The effects of the shape and size of Gd@sub 2@O@sub 3@:Eu nanocrystals on luminescent properties will also be reported.