Since most galaxies in the universe occur in small groups, studies of these environments play an important role in extragalactic astronomy. The recent discovery of diffuse X-ray emission in some groups has provided new perspectives on the dynamics and evolution of such systems. ROSAT studies of groups indicate there are strong correlations between the presence of X-ray emission and the morphological composition of the galaxies in the group. In particular, X-ray emission appears to be absent from groups with a high percentage of spiral galaxies. The X-ray observations also allow the first robust estimates of the total masses and baryon fractions of loose groups. I will discuss these recent X-ray observations and the constraints these observations place on cosmological models.

Although most galaxies occur in small groups, surprisingly little is known about the faint end of the luminosity function in these systems. I will also discuss preliminary results from a multiobject spectroscopy program designed to study the dwarf galaxy population and determine the morphological composition of groups at faint magnitudes for the first time. The new optical data will be compared with existing ROSAT data to look for correlations between the X-ray and optical properties of loose groups.