A workpiece clamping and feeding device e.g. for an automatic sewing machine utilises two belt arrangements (40) arranged side-by-side with an elongated gap (44) extending in a first direction therebetween. The sewing needle path (18) is aligned with the gap (44). The belt arrangements are mounted in a carriage (20) which moves in the first direction while the belts (42) are driven to feed a workpiece clamped therebetween in a second direction extending perpendicularly to the first direction. In this way a workpiece held by the belts can be moved relative to the sewing needle. The workpiece-engaging surface of at least one of the belts (42) of each arrangement (40) is provided with projections (76; 78) on which the workpiece can be held fast. These projections may comprise grit particles (76) or studs, spikes, pins or the like (78). In each case, the particles are sufficiently spaced to enable them to at least indent the surface of the workpiece (and, in the case of e.g. pins, to impale the workpiece) and thus to enhance the holding fast of the workpiece against the surface of the belt.