We have analyzed the electronic populations of chemical bonds and atoms in the highly symmetric closo-carboranes 1,5-C₂B₃H₅ (I) and 1,6-C₂B₄H₆ (II). The overlap populations σ_XY are compared with the corresponding Mulliken indices. We note substantial nonadditivity of the populations σXY for "closed" three-center bonds BCB' and the closeness of the total overlap population σ_t to its maximum value. We have established the localization of the natural MOs on the bonds CH, BH, and BCB', and for molecule I also on the CBC' bonds. The effects of conjugation of bonds in the closo-carborane polyhedron are apparent in the linear dependence of these MOs. The corresponding nonorthogonal hybrid AOs of carbon and boron are also linearly dependent. We have formulated the concept of unshared population of an atom.