A variable compression screw press includes a volume displacing member which overlies the pressure housing feed flight of the screw press. In one embodiment, the volume displacing member is a shroud which may be moved in and out of the intake hopper as desired, without having to disassemble the press. In a second embodiment, the volume displacing member is a hinged gate which can be adjusted to overlie more or less of the pressure housing feed flight. In a third embodiment which may be used in cooperation with either first or second embodiment, the volume within the pressure housing feed flight is partly occupied by block elements removably mounted to the screw flighting of the pressure housing feed flight.