  The evolution of galaxies in groups may have important implications for the
evolution of the star formation history of the universe, since many processes
which operate in groups may suppress star formation and the fraction of
galaxies in bound groups grows rapidly between z=1 and the present day. In this
paper, we present an investigation of the properties of galaxies in galaxy
groups at intermediate redshift (z ~ 0.4). The groups were selected from the
CNOC2 redshift survey as described in Carlberg et al., 2001, with further
spectroscopic follow-up undertaken at the Magellan telescope in order to
improve the completeness and depth of the sample. We present the data for the
individual groups, and find no clear trend in the fraction of passive galaxies
with group velocity dispersion and group concentration. We stack the galaxy
groups in order to compare the properties of group galaxies with those of field
galaxies at the same redshift. The groups contain a larger fraction of passive
galaxies than the field, this trend being particularly clear for galaxies
brighter than M_{B_J} < -20 in the higher velocity dispersion groups. In
addition, we see evidence for an excess of bright passive galaxies in the
groups relative to the field. In contrast, the luminosity functions of the star
forming galaxies in the groups and the field are consistent. These trends are
qualitatively consitent with the differences between group and field galaxies
seen in the local universe.
