Superplastic deformation behavior is examined for Al2O3-based ceramics dispersed with 10 vol% ZrO2 and 10 vol% spinel (MgO .1.3Al(2)O(3)) particles. The maximum tensile elongation obtained is 850% at a strain rate of 5.0x10(-4) s(-1) and at 1500 degreesC. The static grain growth rate of this material is about 0.6 times the growth rate of a Al2O3-10 vol% ZrO2. The dynamic grain growth rate is considerably decreased by the multiple-phase dispersion, which leads to the enhanced superplasticity; large tensile elongation and high available strain rate. Observations of deformed microstructure show spherical ZrO2 particles embedded in elongated Al2O3 grains, suggesting that the primary deformation mechanism would be grain boundary sliding associated with grain boundary diffusion.