Following the inauguration of the Southern African Large Telescope (SALT), the international ELT community met in Cape Town to discuss the next generation of telescopes - those with apertures in excess of 20m. This volume presents the results of their deliberations, starting with reviews of the scientific needs emerging from the exploitation of the present generation of large telescopes and an examination of the technical lessons that might be transferred to larger telescopes. Scientific discussions cover four broad themes: galaxy formation, galaxy evolution and cosmology; stellar populations; the intergalactic medium; and exoplanets and star formation. The status of the various projects is discussed with details of site testing, detector development and an emphasis on adaptive optics which will be critical for these extremely large telescopes. Much of the discussion of IAU S232 is reproduced in detail, providing a real flavour of the controversial issues.