  We calculate the inclusive charmless semileptonic decay width of the B meson
using a QCD-based approach. This approach is able to account for both dynamic
and kinematic effects of nonperturbative QCD. The charmless semileptonic decay
width is found to be enhanced by long-distance strong interactions by +(7\pm
5)% with respect to the free quark decay width. Using the resulting theoretical
value for the charmless semileptonic decay width, an extraction of $|V_{ub}|$
is made from the measured lifetime and inclusive charmless semileptonic
branching ratio of b hadrons.
