Two-loop electroweak corrections to the electron, muon,
and tau lepton anomalous magnetic moments have been
computed recently. Effects of hadronic contributions to the photon
propagator in two-loop QED corrections have also been reanalysed. The
common technique used in both calculations was asymptotic expansion of
Feynman diagrams in the ratio of lepton mass to some heavy mass
scale. In this talk we present some details of this method paying
particular attention to the expansion of multi-scale diagrams.
