Electron--positron annihilation into hadrons plus an
energetic photon from initial state radiation allows the hadronic
cross-section to be measured over a wide range of energies
at high luminosity meson factories. Weighted integrals over this
cross section are a decisive input for electroweak precision tests.
This applies, for example, to the electromagnetic coupling at higher
energies or to the anomalous magnetic moment of the muon.
The radiative return method and the tools needed for such precision
measurement are presented. In particular, a Monte Carlo generator
called PHOKHARA which simulates this process at the next-to-leading
order accuracy is described.