Increasing attention is being focussed on the origin and structure of the Universe. In these studies, analysis of the properties of groups and clusters of galaxies are essential to studies of large-scale structure. Research supported under this grant will be devoted to a study of the structure of groups and clusters of galaxies. Existing databases will be updated. There will also be studies on the cosmological distance scale. The Principal Investigator is regarded as an expert in these areas of study.