Two different interatomic potentials of the embedded atom type were used to study the relationships between dislocation core structure and mobility. Core structures were computed for a variety of dislocations in B2 NiAl. Several non-planar cores were studied as they reacted to applied stress and moved. The results show that in some cases, the dislocation core transforms to a planar structure before the dislocation glides, whereas in some other cases the core retains the non-planar structure at stresses sufficient to sustain glide. The effects of stoichiometry deviations on the core structure and motion were also studied.