The electron pair density, in conjunction with the theory of an atom in a molecule, enables one to unambiguously determine the nature of the bonding between the gallium atoms in bent [HGa-GaH]^2-. The Ga-Ga bonding in the dianion at the experimental bond length is found to be the result of the sharing of two electron pairs at the Hartree-Fock level of theory, the level consistent with the Lewis model of the electron pair.