A booklet 32 is produced from a pre-printed sheet 10 by folding the sheet with at least one but preferably two crease-lines 11 extending in the line of advancement of the sheet. The crease-lines 11 are squeezed by a roller nip 14 and then the sheet is fed to and gripped by a rotatable mandrel 15. The mandrel is rotated to wind the sheet around the outer surface thereof and then the wound sheet 21 is removed from the mandrel and is squeezed through a further roller nip 23 so as to form a substantially flat booklet pre-form 24. The leaves of the pre-form are bound together along at least one compressed folded edge 28 of the pre-form thereby forming a booklet spine and the other three edges are slit open, 25,26,27. Alternatively two spines are formed respectively along the two compressed edges of the pre-form and two or more booklets are formed by cutting through the pre-form part-way between the spines and also slitting open the other two edges 30 of the pre-form.