HERMES is a multi-fibre spectrograph being built for the AAT 3.9m telescope, designed to simultaneously obtain high resolution (R ˜ 28000) spectra for ˜ 400 stars over a 2° field of view. The Galactic Archaeology with HERMES (GALAH) Survey is a major Australian-led project to obtain detailed elemental abundances for a million stars, with the goal of using chemical tagging to decipher the formation history of the Milky Way. For the GALAH Survey, ˜10^6 stars (down to V˜14, at S/N ˜100 / resolution element) will be observed in four passbands, selected to include elements from all major independently-varying element groups, thus allowing direct determination of abundances for each star. The survey will also be directly complementary to wide-area photometric surveys such as Skymapper, and the multidimensional dataset which will come from ESA's Gaia mission.