  The parity violation parameters $A_b$ and $A_c$ of the $Zb{\bar b}$ and
$Zc\bar{c}$ couplings have been measured directly, using the polar angle
dependence of the polarized cross sections at the $Z^0$ pole. Bottom and
charmed hadrons were tagged via their semileptonic decays. Both the electron
and muon analyses take advantage of new multivariate techniques to increase the
analyzing power. Based on the 1993-98 SLD sample of 550,000 $Z^0$ decays
produced with highly polarized electron beams we measure $ A_b = 0.919 \pm
0.030_{stat} \pm 0.024_{syst} $, and $ A_c = 0.583 \pm 0.055_{stat} \pm
0.055_{syst} $.
