Abstract: An automatic tool changer for horizontal spindle multi-function machining centers constructed as a self-contained unit adapted for installation as original equipment or as an accessory. The tool changer has a large capacity magazine and is supported on an independent base so as to avoid the transfer of substantial external loads to the machine elemenets. Tools are transferred between the magazine and spindle by means of a shuttle which carries a two handed transfer arm. Interference with the normal machining motions of the machine is also avoided.