Velocity interferometry diagnostics are used to monitor transmitted compressive shock and release waves in yttria (Y2O3)‐stabilized tetragonal and cubic zirconia. In tetragonal zirconia compressive yielding due to lattice slip or lattice instability is observed at 13–17 GPa and again at 30–31 GPa. This represents an additional fine structure to the dynamic compression of zirconia that has not previously been observed. A correlation with initial sample density is seen for the lower‐amplitude yield. A single yield over the range of the data occurs at 5–6 GPa for cubic zirconia. Approximately 4%–6% porosity in the cubic zirconia accounts for initial yield somewhat lower than earlier studies. From unloading wave profile measurements, initial release wave velocities at the Hugoniot state and stress derivatives of these data are determined. Release moduli data increase monotonically over a Hugoniot stress range of 11–45 GPa. A stress derivative of this data ofK’l= 1.85 is obtained. Stress derivatives determined directly from the initial release slope of individual profiles are significantly higher and suggest deformation or phase transformation kinetics on release. Release waves from Hugoniot states of 11–13 GPa suggest formation of a rarefaction shock and may imply a dynamic stress‐induced transformation not indicated by the shock profile. A tensile spall strength of 1.6 GPa was determined for the tetragonal zirconia. This high value may be related to the large fracture toughness of this transformation‐toughened ceramic.