A model for the molecular interaction of N2 with graphite is proposed which is derived from successful treatments of the energies of rare gases on graphite and of the N2-N2 interaction. The non-spherical shape of this molecule is explicitly taken into account in the gas-solid energy ; in addition, the interaction of a pair of adsorbed N2 molecules indudes the quadrupolar energy as well as non-sphencity. Calculated energies are in good agreement with estimates obtained from the experimental heats of adsorption. Barriers to rotation and to translation across the surface are estimated and used to characterize the states of motion in some of the recently discovered ordered phases in this system