  Two-dimensional surface photometry derived from Hubble Space Telescope
imaging is presented for a sample of 225 early-type galaxies (assumed to be
cluster members) in the fields of 9 clusters at redshifts $0.17 < z < 1.21$.
The 94 luminous ellipticals ($M_{AB}(B)<-20$; selected by morphology alone with
no reference to color) form tight sequences in the size-luminosity plane. The
position of these sequences shifts, on average, with redshift so that an object
of a given size at z=0.55 is brighter by $\Delta M(B)=-0.57 \pm 0.13$ mag than
its counterpart (measured with the same techniques) in nearby clusters. At
z=0.9 the shift is $\Delta M(B)=-0.96 \pm 0.22$ mag. If the relation between
size and luminosity is universal so that the local cluster galaxies represent
the evolutionary endpoints of those at high redshift, and if the
size-luminosity relation is not modified by dynamical processes then this
population of galaxies has undergone significant luminosity evolution since z=1
consistent with expectations based on models of passively evolving, old stellar
populations.
