  The oscillation frequency of B0-B0bar mixing (Delta-m_d) has been measured
using 29.1 fb^{-1} of datacollected with the Belle detector at KEKB. This
measurement is made through the distributions of the proper decay time
difference of B pairs in events tagged as same- and opposite-flavor decays. In
each event, one $B$ is fully reconstructed in a flavor-specific hadronic decay
mode, while the flavor of the other is extracted through a likelihood
calculated from the b-flavor information carried in its final decay products.
We obtain Delta-m_d = (0.528 +- 0.017 +- 0.011) ps^{-1}, where the first error
is statistical and the second error is systematic.
