Though the beta and gamma forms of the simplest amino acid, glycine, yield a variety of different phases on application of pressure, Raman data suggest that the most common alpha form of glycine persists to 20 GPa. In this experiment neutron powder diffraction data will be collected to 19 GPa, the anvil limit currently available on the PEARL instrument. This will be one of the highest pressure yet applied to an organic crystal structure. The results will enable the spectroscopic results to be tested, and provide data suitable for determination of the equation of state of alpha glycine. This will permit mechanical properties of alpha glycine to be compared to those of other phases, and the differences in phase behaviour understood in terms of the differing packing motifs which characterise their crystal structures.