  The quadrupolar ordering in CeB_6 is explained in terms of the electrostatic
interaction of quadrupolar moments arranged into a simple cubic lattice. The
representation of magnetic and quadrupolar moments by means of quasispins of
two kinds is employed. A linear increase of the quadrupolar transition
temperature T_Q(H) with applied magnetic field and its further re-entrance are
described using a generalized spherical model which is well adjusted to a
particular problem of the quadrupolar ordering in CeB_6. The theory naturally
explains the growing specific heat jump at T_Q(H) with increasing magnetic
field. The role of the quadrupolar ordering in the formation of the magnetic
ordering, as well as the possible critical experiments and applications to
other rare-earth compounds, are discussed.
