  The precision measurements of lepton electroweak parameters at SLD and LEP
are reviewed and discussed. The updated SLD weak mixing angle measurement from
$A_{LR}$ and the lepton left-right forward-backward asymmetries is
$\sin^2\theta_W^{eff} = 0.23099 \pm 0.00026$, and the combined SLD/LEP
lepton-based value is $0.23119 \pm 0.00020$. This value differs by over
$3\sigma$ from the comparable quark-based value.
