It is demonstrated that for diamond an extension of the pseudopotential theory using t matrices yields covalent bonding. The covalent bonds arise from multiple scattering of the valence electrons by the lattice ions. It is estimated that about 1.2 valence electrons are localized per bond. We obtain approximately -0.45 rydberg for the cohesive energy. The experimental value for the cohesive energy of diamond is -0.54 rydberg. An approximate expression for the self-consistent crystal field is given in terms of multipole fields. The determination of lattice force constants, fundamental in lattice dynamics, is discussed.