  We present the first spectroscopic survey of intrinsically low Lx clusters at
z>>0, with HST WFPC2 imaging and ground-based spectroscopy. We study 172
confirmed cluster members in a sample of ten clusters at z=0.23-0.3, with
Lx<4.E43 h^{-2} ergs/s. The core of each cluster is imaged with WFPC2 in the
F702W filter, and the spectroscopic sample is statistically complete to
Mr-19.0+5log(h), within an 11' field. The clusters are dynamically
well-separated from the surrounding field and the velocity dispersions range
from ~350-850 km/s. Emission line galaxies in these clusters are relatively
rare, comprising only 22 +/- 4% of the sample. There is no evidence that these
emission-line galaxies are dynamically distinct from the majority of the
cluster population, though our sample is too small to rule out the ~30%
difference that has been observed in more massive clusters. We find eleven
galaxies, comprising 6% of the cluster members, which are disk-dominated but
show no sign of emission in their spectrum. Most of these are relatively
isolated, spiral galaxies with smooth disks. We find no cluster members with a
starburst or post-starburst spectrum. The striking similarity between the
spectral and morphological properties of galaxies in these clusters and those
of galaxies in more massive systems at similar redshifts implies that the
physical processes responsible for truncating star formation in galaxies are
not restricted to the rare, rich cluster environment, but are viable in much
more common environments. In particular, we conclude that ram pressure
stripping or cluster-induced starbursts cannot be solely responsible for the
low star formation rates in these systems.
