Nonagglomerated spherical ZrO2 particles of 5-8 nm size were made by emulsion precipitation. Their crystallization and film-forming characteristics were investigated and compared with nanosized ZrO2 powders obtained by sol-gel precipitation. High-temperature X-ray diffraction indicated that the emulsion-derived particles are amorphous and crystallize at 500degreesC into tetragonal zirconia, which is stable up to 1000degreesC. Crystallite growth from 5-20 nm occurred between 500degrees-900degreesC. Films of 6-75 nm thickness were made by spreading, spin coating, and controlled deposition techniques and annealed at 500degrees-600degreesC. The occurrence of t-ZrO2 in the emulsion-precipitated powder is explained by the low degree of agglomeration and the corresponding low coarsening on heating to 500degrees-800degreesC, whereas the agglomerated state of the sol-gel precipitate powder favors the occurrence of the monoclinic form of zirconia under similar conditions.