Electroweak Precision Measurements with Leptons

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.