  We review some of the few available nonadiabatic calculations of dipole
moments. We show that those carried out in a laboratory-fixed set of coordinate
axes are bound to fail and discuss the more reasonable ones in a molecule-fixed
reference frame. For completeness we also describe the standard
Born--Oppenheimer calculations of dipole moments. We briefly address the
experimental estimation of dipole moments from the Stark shift of spectral
lines and argue that it does not provide such property but a sort of
energy--weighted average of dipole transition moments.
