We present a measurement of the mass difference Delta m_d for the
B^0 meson and the statistical power of the b flavor tagging methods used.  The
measurement uses 90 pb^-1 of data from ppbar collisions at sqrt s = 1.8 TeV
collected with the CDF detector.  An inclusive lepton trigger is used to
collect a large sample of B hadron semileptonic decays.  The mass difference
Delta m_d is determined from the proper time dependence of the fraction of B
hadrons that undergo flavor oscillations.  The flavor at decay is inferred
from the charge of the lepton from semileptonic B decay.  The initial flavor
is inferred by determining the flavor of the other B hadron produced in the
collision, either than its semileptonic decay (soft-lepton tag) or from its
jet charge.  A measurement yields Delta m_d = 0.500 +/- 0.052 +/- 0.043 h-
ps^-1, where the first uncertainty is statistical and the second uncertainty
is systematic.  The statistical powers (e D^2) of the soft-lepton and
jet-charge flavor taggers are (0.91 +/- 0.10 +/- 0.11)% and (0.78 +/- 0.12 +/-
0.08)%, respectively.