A molecular orbital study of 2,3-dinaphthylene is reported, the molecule being assumed to have a planar structure. The magnitude of the resonance energy shows that the interaction of the π electrons as a whole is quite strongly stabilizing. The bond orders have been computed and from these the lengths of the bonds in the molecule have been deduced. The longest wave length in an allowed excitation probably arises from a transition between mobile electron levels of symmetryA1g → B1uand polarized in the direction of the long axis of the molecule.