  We have obtained new deep optical and near-infrared images of the field of
the radio-loud quasar 1335.8+2834 at $z=1.086$ where an excess in the surface
number density of galaxies was reported by Hutchings et al. [AJ, 106, 1324]
from optical data. We found a significant clustering of objects with very red
optical-near infrared colors, $4 \lesssim R-K \lesssim 6$ and $3 \lesssim I-K
\lesssim 5$ near the quasar. The colors and magnitudes of the reddest objects
are consistent with those of old (12 Gyr old at z=0) passively-evolving
elliptical galaxies seen at $z=1.1$, clearly defining a `red envelope' like
that found in galaxy clusters at similar or lower redshifts. This evidence
strongly suggests that the quasar resides in a moderately-rich cluster of
galaxies (richness-class $\geq 0$). There is also a relatively large fraction
of objects with moderately red colors ($3.5 < R-K < 4.5$) which have a
distribution on the sky similar to that of the reddest objects. They may be
interpreted as cluster galaxies with some recent or on-going star formation.
