  Using a homogenous sample of 38,208 quasars with a sky coverage of $4000 {\rm
deg^2}$ drawn from the SDSS Data Release Five quasar catalog, we study the
dependence of quasar clustering on luminosity, virial black hole mass, quasar
color, and radio loudness. At $z<2.5$, quasar clustering depends weakly on
luminosity and virial black hole mass, with typical uncertainty levels $\sim
10%$ for the measured correlation lengths. These weak dependences are
consistent with models in which substantial scatter between quasar luminosity,
virial black hole mass and the host dark matter halo mass has diluted any
clustering difference, where halo mass is assumed to be the relevant quantity
that best correlates with clustering strength. However, the most luminous and
most massive quasars are more strongly clustered (at the $\sim 2\sigma$ level)
than the remainder of the sample, which we attribute to the rapid increase of
the bias factor at the high-mass end of host halos. We do not observe a strong
dependence of clustering strength on quasar colors within our sample. On the
other hand, radio-loud quasars are more strongly clustered than are radio-quiet
quasars matched in redshift and optical luminosity (or virial black hole mass),
consistent with local observations of radio galaxies and radio-loud type 2 AGN.
Thus radio-loud quasars reside in more massive and denser environments in the
biased halo clustering picture. Using the Sheth et al.(2001) formula for the
linear halo bias, the estimated host halo mass for radio-loud quasars is $\sim
10^{13} h^{-1}M_\odot$, compared to $\sim 2\times 10^{12} h^{-1}M_\odot$ for
radio-quiet quasar hosts at $z\sim 1.5$.
