  The importance of horizontal branch and RR Lyrae stars is discussed in the
context of cosmological arguments for the formation of the Galactic halo and
its satellite dwarf galaxies. It is shown, in particular, that the Galactic
halo globular cluster system cannot have formed from the accretion of
``protogalactic fragments'' resembling the very early counterparts of the
present-day dwarf satellite galaxies of the Milky Way, or else its RR Lyrae
properties would be very different from what is currently observed.
