We present a molecular dynamics study of the interactions between two molecules of naphthalene present at air-water versus air-ice interfaces. In agreement with the inference from our previous experimental work [Kahan, T. F.; Donaldson, D. J. J. Phys. Chem. A 2007, 111, 1277], the results suggest that self-association of the molecules is more likely to take place on the ice surface than on the water surface. A shorter average distance between the two naphthalene molecules, in conjunction with a stronger interaction energy and free energy of association, point to a stronger tendency to self-associate oil ice than on water. The distinct behavior at the two interfaces appears be due to more favorable interactions between naphthalene molecules on liquid water surfaces than on ice surfaces.