As has been recognized for some time, the dispersion interaction of molecules, particularly large molecules, cannot be adequately represented by a simple London-type expression based on the total molecule polarizabilities. We investigate two models consisting of several anisotropic polarizabilities associated with molecular subgroups. In one model intramolecular interactions among the groups are included; in the other only intermolecular interactions are included, but different "effective" polarizabilities are used. These models are generalizations of models considered previously by others. We calculate the interaction energy as a function of molecular separation for several different relative orientations of the molecular axes of model PAA (p-azoxyanisole) molecules. We find that (1) at very short distances intramolecular interaction is negligible; (2) at intermediate distances the distance dependence is approximately inverse fifth power; (3) the two models yield almost identical results over all but the very shortest distances; (4) at molecular separations greater than a few times the largest molecular dimension, the distance dependence is essentially the simple inverse sixth power London interaction based on total molecular polarizability. We compare these qualitative results with those found previously by others.