Abstract: A book stiffener comprises a relatively flat, thin, elongated, ridged, rotatable strip (32) having a length dimension (38) substantially greater than a width (44) of a back binding (22) of a book cover (16) but less than a length (46) of the book cover and a width dimension which is less than the length (40) of the back binding and a swivel attachment (34, 30) for attaching the rotatable strip to a rear surface of the book cover so as to allow rotation of the rotatable strip relative to the book cover whereby the rotatable strip can be rotated to a position in which it extends across hinge seams (24, 26) of front and back flap covers (18, 20) of the book cover with the back binding off the book to thereby impinge upon the front and back flap covers to prevent them from being opened substantially beyond an approximate common plane.