  I discuss the theoretical uncertainties in the extraction of $|\,V_{cb}|$
from semilep\-to\-nic decays of $B$ mesons, taking into account the most recent
theoretical developments. The main sources of uncertainty are identified both
for the exclusive decay mode $B\to D^*\ell\,\bar\nu$ and for the inclusive
channel $B\to X\,\ell\,\bar\nu$. From an analysis of the available experimental
data, I obtain $|\,V_{cb}|_{\rm excl} = 0.041\pm 0.003_{\rm exp}\pm 0.002_{\rm
th}$ from the exclusive mode, and $|\,V_{cb}|_{\rm incl} = 0.040\pm 0.001_{\rm
exp}\pm 0.005_{\rm th}$ from the inclusive mode. I also give a prediction for
the slope of the form factor ${\cal{F}}(w)$ at zero recoil, which is
$\widehat\varrho^2=0.8\pm 0.3$.
