A leaflet is produced from a pre-printed sheet of material by folding the sheet with at least one crease-line along the line of advancement of the sheet but preferably with two or more such crease-lines so that the sheet is fan-folded. The crease-lines are squeezed by a roller nip and then the sheet is fed into a diametral slot in a mandrel of elliptical cross-section. The leading edge of the sheet is gripped within the slot and then the mandrel is rotated to wind the sheet around the outer surface thereof. The wound sheet is then removed from the mandrel and is squeezed through a roller nip so as to form a substantially flat folded leaflet. The leaflet may be converted to a booklet by joining together the overlying sheets along one folded edge of the compressed leaflet and slitting open the other folded edge of the compressed leaflet.
