  We presents results for the matrix elements of a variety of four-fermion
operators calculated using quenched Wilson fermions. Our simulations are done
on 170 lattices of size $32^3 x 64$ at $\beta = 6.0$. We find $B_K=0.74 +- 0.04
+- 0.05$, $B_D= 0.78 +- 0.01$, $B_7^{3/2}= 0.58 +- 0.02 {+0.07 \atop -0.03}$,
$B_8^{3/2}= 0.81 +- 0.03 {+.03 \atop -0.02}$, with all results being in the NDR
scheme at $\mu=2 GeV$. We also calculate the B-parameter for the operator
$\CQ_s$, which is needed in the study of the difference of B-meson lifetimes.
Our best estimate is $B_s(NDR,\mu=1/a)=0.80 +- 0.01$. This is given at the
lattice scale since the required 2-loop anomalous dimension matrix is not
known. In all these estimates, the first error is statistical, while the second
is due to the use of truncated perturbation theory to match continuum and
lattice operators. Errors due to quenching and lattice discretization are not
included. We also present new results for the perturbative matching
coefficients, extending the calculation to all Lorentz scalar four-fermion
operators, and using NDR as the continuum scheme.
