  $B^0_d$-$\bar{B}{}^0_d$ oscillations are observed in ``self-tagged'' samples
of partially reconstructed $B$ mesons decaying into a lepton and a charmed
meson collected in $p\bar p$ collisions at $\sqrt{s} = 1.8$ TeV. A flavor
tagging technique is employed which relies upon the correlation between the
flavor of $B$ mesons and the charge of nearby particles. We measure the flavor
oscillation frequency to be $\Delta m_d = 0.471 ^{+0.078}_{-0.068} \pm 0.034
ps^{-1}$. The tagging method is also demonstrated in exclusive samples of
$B^+_u \to J/\psi K^+$ and $B^0_d \to J/\psi K^{*0}(892)$, where similar
flavor-charge correlations are observed. The tagging characteristics of the
various samples are compared with each other, and with Monte Carlo simulations.
