  We have measured the B hadron energy distribution in Z0 decays using a sample
of semi-leptonic B decays recorded in the SLD experiment at SLAC. The energy of
each tagged B hadron was reconstructed using information from the lepton and a
partially reconstructed charm-decay vertex. We compared the scaled energy
distribution with several models of heavy quark fragmentation. The average
scaled energy of primary B hadrons was found to be <x_E_B> = 0.716 +- 0.011
(stat.) +0.022 -0.021 (syst.).
