  We calculate the hadronic tensor for inclusive semileptonic B decay to
O(alpha_s). This allows O(alpha_s Lambda_{QCD}/mb) corrections to hadronic
invariant mass observables to be directly evaluated with experimentally
required cuts on phase space. Several moments of phenomenological interest are
presented to O(alpha_s Lambda_{QCD}/mb) and O(Lambda_{QCD}^3/mb^3), allowing a
consistent extraction of the HQET parameters up to O(Lambda_{QCD}^3/mb^3) and
the b quark mass with theoretical error ~ 50 MeV. The hadronic invariant mass
spectrum is examined with a general moment to obtain observables that test the
theoretical error estimate assigned to these parameters; in particular,
fractional moments that directly test the OPE for inconsistencies in the
hadronic invariant mass spectrum are reported. The mb Lambda_{QCD}/mc^2
expansion present for fractional moments of the hadronic invariant mass spectum
is discussed and shown to introduce a numerically suppressed uncertainty of
O(mb^4 Lambda_{QCD}^4/mc^8).
