Electric field gradient lattice sums for the vacancy-disordered and vacancy-ordered forms of maghemite were evaluated using a point charge model. The calculated electric field gradients produced a wide range of magnitudes and principal directions for the quadrupole interaction for both forms of maghemite. Small perturbations of the crystallographic parameters were shown to have a significant effect on the quadrupole shift. The effects observed were significant enough to show that quadrupole shifts should be considered when fitting the Mössbauer spectra of maghemite.The Effect of Vacancy Ordering on Quadrupole Shifts in Mössbauer Spectra of Maghemite. K.M.Spiers, D.M.Paganin, J.D.Cashion: Journal of Physics - Condensed Matter, 2011, 23[17], 176004