  Using recent results for nonperturbative contributions to the $B$ and $D$
meson inclusive semileptonic widths, a model independent extraction of $\vbc$,
$m_c$ and $m_b$ is made from the experimentally measured $B$ and $D$ lifetimes
and semileptonic branching ratios. Constraining the parameters of the HQET at
$\CO(1/m_Q^2)$ by the $D$ semileptonic width, $\vbc$ is found to lie in the
range $.040<\vbc< 0.057$. The $c$ and $b$ quark masses are not well constrained
due to uncertainty in the relevant scale of $\alpha_s$. These results assume
the validity of perturbative QCD at the low scales relevant to semileptonic
charm decay. Without making this assumption, somewhat less stringent bounds on
$V_{bc}$ from $B$ decay alone may be obtained.
