Cadmium sulfide crystals were shocked along the crystalcaxis to peak stresses ranging between 18 and 75 kbar. Stress-time profiles were measured both at the impact surface and after transmission through 1 to 2-mm-thick samples. Detailed analysis of the present data in combination with published static results makes a persuasive case for the completion of the wurtzite to rocksalt phase change in less than 0.2 &mgr;s under shock loading. The main findings are: the transition stress is measured to be32.5±1 kbar;transformation to the final state is a two step process with the first step being too rapid (less than 10 ns) to be observed in our experiments and the second step occurring in 0.1 to 0.2 &mgr;s; the transition occurs directly from the elastic state prior to any plastic deformation. The calculated mean stress for the transition is 22.9 kbar in good agreement with the 23 kbar pressure reported in static high pressure studies; the presence of large shear stress has no effect on the transition pressure. Our results suggest that the onset of the phase transition results in plastic deformation and, subsequently, the phase transition and plasticity are coupled under shock loading. ©1997 American Institute of Physics.