This proposal seeks to explore the high-pressure structural behaviour of N,N¿-dimethylurea. Two new high-pressure forms have been structurally characterised using x-ray methods, but the accurate location of hydrogen atoms remains challenging. Such a relatively simple system also lends itself to crystal structure prediction (CSP) methodologies and so CSP calculations have been performed in order to explore fully the phase behaviour of N,N¿-dimethylurea. All four experimental forms are identified by the calculations, but as usual with such calculations numerous structures with very similar lattice energies are predicted. The challenge is to discriminate between these structures and identify which are in fact plausible, experimentally accessible structures. The study will therefore explore whether there are other forms accessible at higher pressures and at higher/lower temperatures.