The compaction response of CeO2 powders with two distinct morphologies ranging in size from 300 nm to 10-14 μm are investigated through quasi-static and dynamic compaction experiments. In the quasistatic and low pressure dynamic regimes the high aspect ratio 10-14 μm particles exhibit a measurably stiffer response. However, as pressure increases in the dynamic regime a transition occurs suggesting shape effects dominate at low pressures while particle size becomes more important at higher pressures. Transmitted wave profiles are examined, and suggest non-equilibrium processes may occur following the initial compaction front. Furthermore, three formulations of the P-α model are applied to the 300 nm compaction data, and a power law relation is found to yield the best fit to experimental data.