Using the densities and space distributions of local RR Lyrae stars
and their prognitors, we estimate the efficiency of RR Lyrae
production for the old thin disk, the thick disk, and the metal-weak
thick disk, relative to the halo.  We find that the RR Lyraes form
from the thick disk ([Fe/H] > -1.0) horizontal branch (HB) stars with
about 1/40 the frequency that they do in the halo.  The ratio is about
1/800 for the old thin disk, and about 1/25 for the metal-weak thick
disk ([Fe/H] <= -1.0).  The production efficiency increases with
decreasing metal abundance, as if the bulk of the HB stars moves
blueward toward the instability strip.  In each of the 3 disk
sub-populations, it appears that only the extreme tail of the HB star
distribution reaches blueward into the instability strip.  

We find the formation efficiency of RR Lyraes in disk globular
clusters to be about equal to that for the thick disk RR Lyraes in the
field.  That is, the small number of RR Lyrae stars observed in disk
clusters, relative to the field thick disk RR Lyraes, is largely due
to the small number of progenitors available in the clusters, relative
to the field within several kiloparsecs of the Sun.  Some of the RR
Lryae stars in disk globular clusters appear to have anomalously long
periods relative to the field RR Lyraes of similar abundance.  This
may be related to the denser stellar environments of the clusters, and
may be a red-HB manifestation of the extended blue HBs seen in many
dense clusters at low abundances.