  Field W UMa binaries observe a well known Period-Color Relation such that
systems containing more massive stars are bluer and have longer orbital periods
than those systems with lower mass components. However, it has been known for a
decade that metal-poor W UMa's are too blue, have too short an orbital period,
or both. Correcting the observed color for the reduced line blanketing in the
atmosphere of a Pop II star only accounts for part of the observed discrepancy.
As others have suggested, and Rucinski (2000) show, the smaller radii of Pop II
stars and the correspondingly shorter orbital periods are responsible for the
remainder. In this paper I investigate the effect of evolution upon the
location in the period-color plane. This paper addresses the restricted case of
equal mass components in critical contact with their inner Roche lobes, but
should be applicable to the more general cases to the extent that the relative
sizes of stellar components are preserved with metallicity changes.
  The calculated metallicity-age dependent Period-Color Relations substantially
agree with Rucinski & Duerbeck's (1997) empirically derived corrections to the
Period-Color Relation over most of the investigated range of periods. However,
our predictions deviate to a greater degree as stellar age increases since
their parameterization does not include the effect of evolution.
