Schottky barrier electroreflectance spectra are reported for GaSb from 0.6 to 26 eV. Accurate energies are determined for a number of critical points between the sp3 and Ga−3d valence bands and the conduction bands. The energy of XV7 is shown to lie at least 3 eV below ΓV8. This is below the value obtained from local pseudopotential calculations and the x-ray photoemission assignments, but follows a trend previously established by nonlocal pseudopotential calculations for Ge and GaAs. The Ga 3d-XC6 exciton binding energy is of the order of 100 meV.