A device for processing material by mixing and/or plasticization or agglomeration has a screw housing, in which at least two screws are situated adjacent to one another. The screw channels are engaged with one another. The screws are driven to rotate by at least one motor. The screws are supplied with the material through an intake opening of the screw housing and the processed material leaves the screw housing through at least one outlet opening. An apparatus is provided, which in operation of the device provides the gap which exists between adjacent screw channels of the screws alternately with a periodic enlargement or reduction, which is superimposed on the rotational movements of the two screws. In the method for material processing, the material, in addition to the compaction which is caused by the conveyance action of the screws, is subjected to periodic squeezing by the screws.