  We have made a survey of quasar environments at 0.5 < z < 0.8, using a sample
of both radio-loud and radio-quiet quasars matched in B-band luminosity. Our
observations include images of background control fields to provide a good
determination of the field galaxy counts. About 10 per cent of the quasars
appear to live in rich clusters, whereas approximately 45 per cent live in
environments similar to that of field galaxies.
  The richness of galaxies within a 0.5 Mpc radius around the radio-quiet
quasars is found to be indistinguishable from the richness around the
radio-loud quasars, corresponding on average to groups or poorer clusters of
galaxies. Comparing the galaxy richness in the radio-loud quasar fields with
quasar fields in the literature, we find no evidence of an evolution in the
environment with epoch. Instead, a weak, but significant correlation between
quasar radio luminosity and environmental richness is present. It is thus
possible that the environments of quasars, at least the powerful ones, do not
evolve much between the present epoch and z \approx 0.8.
