  We investigate the effects induced by excited leptons, at the one-loop level,
in the anomalous magnetic and weak-magnetic form factors of the leptons. Using
a general effective Lagrangian approach to describe the couplings of the
excited leptons, we compute their contributions to the weak-magnetic moment of
the $\tau$ lepton, which can be measured on the $Z$ peak, and we compare it
with the contributions to $g_\mu - 2$, measured at low energies.
