The very high electron mobility of GaAs, aided by the use of semi-insulating GaAs substrate material, makes possible the achievement of very high switching speed (τd< 100ps) integrated circuits which can simultaneously exhibit very low dynamic switching energies (PDτd< 100fJ). Planar GaAs circuits of this performance have already been demonstrated. Such circuits, with < 1000µm2gate areas, open the way to an extremely high performance, very dense, low power VLSI technology. It is the purpose of this paper to summarize the reasons why GaAs is so attractive for high performance ICs, to review the present status of GaAs IC development efforts and their results for MSI and upper MSI (near LSI) circuits, and to explore the prospects for the extension of this technology into the VLSI regime.