Forty five radio sources will be selected from the third Cambridge (3C) "1 Jansky" catalog; the Parkes, Australia "0.1 Jansky" catalog; and the Leiden Berkeley Deep Survey (LBDS). Galaxies having redshifts close to 0.45 will be studied in the optical, infrared and radio wavebands. This sample spans 4 orders of magnitude in radio luminosity at a single cosmic epoch, corresponding to a look-back time of roughly 30% of the age of the Universe. This is ideal for differentiating between the effects of epoch and power radiated. Specific analyses will be made of the colors and stellar populations of the radio-galaxies, their optical morphology, the strength of the nuclear and extra nuclear line emission, the density and nature of the their cluster environments and the morphology and power of the radio source itself. Relationships between these properties will be sought, and direct comparisons with the radio source population at the present epoch and with the non-radio population at z ~ 0.45 will be made. In addition, the nature and evolution of the other galaxies in the clusters will be examined and compared with existing data on the `Butcher-Oemler' clusters. This will significantly extend the range of high redshift clusters studies and may illuminate links between the evolution of the environment and the radio sources.
