The bluer populations of galaxies reported many years ago by Butcher
and Oemler and the recent HST images of these clusters suggest that
more star formation has gone on in the past in rich clusters. Higher
redshift HST images of the cluster around 3C324 at z = 1.2 suggests
that even more activity is occurring at this epoch. The well-known
relation between radio continuum emission and far IR dust emission
shows that star formation and centimeter continuum emission are
closely linked. Thus using the signature of star formation we can
probe the recent activity level in distant rich clusters in the radio.
However, to reach the necessary radio luminosities we are limited to
z 
now. The enhanced VLA will be able to reach these same
luminosities at 
, increasing the look-back time from about
50% to about 75% of a Hubble time. (
)