We compare (V-I)(0)-(V-K)(0) color-color and (V-I)(0)-log P period-color di
agrams for Baade's window and local RRab Lyrae stars. We iind that for a fi
xed log P, the Baade's window RR Lyrae stars are similar to 0.17 mag redder
in (V-I), than the local RR Lyrae stars. We also show that there is no suc
h effect observed in (V-K)(0). We argue that an extinction misestimate towa
rd Baade's window is not a plausible explanation of the discrepancy. Unlike
Baade's window RR Lyrae stars, the local ones follow a blackbody color-col
or relation and are well approximated by theoretical models. We test two pa
rameters, iron metallicity and surface gravity, and find that their effects
are too small to explain the (V-I)(0) discrepancy between the two groups o
f stars. We suggest that the anomalous (V-I), behavior of the Baade's windo
w RR Lyrae stars may be caused by an enhancement in alpha-element abundance
. We note that a similar color discrepancy for clump giant stars has been r
ecently reported by Paczynski, and we caution that RR Lyrae stars and clump
giants, often used as standard candles, can be subject to the same type of
systematics.