  The shape of the lepton spectrum in inclusive semileptonic $B\to
X\,\ell\,\bar\nu_\ell$ decay is sensitive to matrix elements of the heavy quark
effective theory, $\bar\Lambda$ and $\lambda_1$. From CLEO data we extract
$\bar\Lambda=0.39\pm0.11\,$GeV and $\lambda_1=-0.19\pm0.10\,{\rm GeV}^2$, where
the uncertainty is the $1\sigma$ statistical error only. Systematic
uncertainties are discussed. These values for $\bar\Lambda$ and $\lambda_1$ are
used to determine $|V_{cb}|$ and the $\overline{\rm MS}$ bottom and charm quark
masses. We discuss the theoretical uncertainties related to order
$(\Lambda_{\rm QCD}/m_b)^3$ effects and higher orders in the perturbative
expansion.
