  We discuss the impact of mixing and rotation along the red-giant branch (RGB)
on the properties of horizontal-branch (HB) stars with emphasis on two
problems: the nature of the unexpected blue HB population in the metal-rich
globular clusters (GCs) NGC 6388 and NGC 6441 and the cause of the low
gravities in the blue HB stars. New stellar models indicate that the sloped HBs
in NGC 6388 and NGC 6441 might arise from a spread in metallicity, implying
that these GCs may be metal-rich analogues of omega Cen. The low gravity
problem can be largely explained by the radiative levitation of Fe in the
atmospheres of the blue HB stars. We show that the onset of radiative
levitation and the drop in HB rotation velocities at Teff ~ 11,000 K coincide
with the disappearance of surface convection. The low rotation velocities of
the hotter HB stars may be due to the spin down of the surface layers by a weak
stellar wind induced by the radiative levitation of Fe. We conclude that the
impact of mixing and rotation on the HB remains to be clearly established.
