  We present a study of the color evolution of elliptical and S0 galaxies in
six clusters of galaxies inside the redshift range 0.78 < z < 1.27. For each
cluster, we used imaging from the Hubble Space Telescope to determine
morphological types by both an automated technique and from visual inspection.
We performed simulations to determine the accuracy of the automated
classifications and found a success rate of ~75% at m(L*) or brighter
magnitudes for most of our HST imaging data with the fraction of late--type
galaxies identified as early--type galaxies to be ~10% at m(L*) to ~20% at
m(L*)+2. From ground based optical and near-infrared imaging, we measured the
zero-point and scatter in the color--magnitude relation of the early-type
populations, which when combined with Stanford et al. (1998), yields a sample
of cluster early--type galaxies that span a lookback time of 9 gigayears from
the present. We see the colors of the early--type cluster members become bluer
with increasing redshift. We fit a set of models to the change in the color as
a function of redshift with the best fitting values ranging from a formation
redshift of 3^+2_-1 to 5_-3. The large scatter in resulting formation epochs,
which depends on the details of the models used, implies that we can conclude
that the oldest stars in the elliptical galaxies appear to have formed at
redshifts of z>3. We find possible evolution in the scatter of the colors, with
some high redshift clusters showing scatter as small as the Coma cluster but
others showing much larger scatter. Those clusters with a small scatter imply
either a formation redshift of at least z ~ 3 or a smaller spread in the range
of formation redshifts at lower redshifts, assuming a Gaussian distribution of
star-formation around the mean epoch.
