  This paper discusses the galaxy populations of three rich clusters, with
redshift 0.19 (0839+29), 0.24 (1231+15), and 0.32 (1224+20), from the database
of the CNOC1 consortium. The data consist of spectra of 52 cluster members for
0839+29, 30 members for 1224+15, and 82 members for 1231+15, and there are
comparable numbers of field galaxy spectra. 0839+29 is compact with no strong
radial gradients, and possibly dusty. 1224+20 is isolated in redshift, has low
velocity dispersion around the cD galaxy, and low 4000A break. 1231+15 is
asymmetrical and we discuss the possibility that it may be a recent merger of
two old clusters. We find few galaxies in 0839+29 and 1231+15 with ongoing or
recently truncated star-formation.
