9320715 Impey This project involves a systematic study of the properties of quasars, using the recently completed Large Bright Quasar Survey (LBQS). The objective and quantifiable selection criteria for the LBQS will allow a calculation of the probability of detecting a quasar as a function of redshift and optical luminosity. There will be a determination of the sensitivity of derived quantities such as the luminosity function to the shape of the spectral energy distribution. The Principal Investigators will continue deep and shallow radio observations of the LBQS, in order to understand the bimodal distribution of radio luminosity. The environments and host galaxies of low redshift quasars (0.4 < z < 1) from the LBQS will be studied. The Principal Investigators will construct global energy distributions from radio to X-ray wavelengths for subsamples of the LBQS, in order to compare to the space density and evolution of quasars selected at other wavelengths. In addition to continuing to exploit the LBQS, the Principal Investigators will begin two new quasar surveys. The first will use red objective prism plates to look for rare populations of bright and high redshift (2 < z < 4) quasars. The second will use a multicolor digital sky survey to isolate large numbers of high and low redshift quasars, sufficient for studies of clustering and for a major improvement in our understanding of the luminosity function.