We have measured the B hadron energy distribution in Z(0) decays using
a sample of semileptonic B decays recorded in the SLD experiment at S
LAG. The energy of each tagged B hadron was reconstructed using inform
ation from the lepton and a partially reconstructed charm-decay vertex
. We compared the scaled energy distribution with several models of he
avy quark fragmentation. The average scaled energy of primary B hadron
s was found to be (x(EB))=0.716+/-0.011(stat)(-0.022)(+0.021)(syst).