Dual-stage, constant loading-rate followed by constant-load, pyramidal indentation experiments were performed to investigate the strain-rate (10−5–10−1/s) and temperature (295–573 K) dependence of pure magnesium. The estimated total activation energy, Q (0.69–1.01 eV), and apparent activation volume, V* (17–28b3), indicate that plastic deformation is controlled by a dislocation cross-slip mechanism. The results from this work and previous studies confirm that, during pyramidal indentation of Mg, the operative deformation mechanism remains the same over a very wide strain-rate and temperature range.