A study is made of the connection between a one-electron model hamiltonian of the Anderson-Hubbard type and the electronegativity, both for free atoms and for simple binary compounds. Non-linear terms in the valence electron occupation number must be included in the hamiltonian in addition to the usual linear tenn. It is found that interatomic interactions occurring in the compound increase the non-linearity substantially over that for the separated atomic constituents. This approach improves the physical understanding of the connection between the clectronegativities of the cation and the anion and (1) the Fermi energies (work functions) of solid compounds and (2) charge transfer in heteronuclear molecules. Charge transfer is specifically discussed for donor-acceptor organic solids and for strongly polar molecules with mutual cation-anion polarization effects included. © 1981.