Abstract: A method and an apparatus for manufacturing book blocks from various printed sheets composed of a plurality of quarto sheets which are inserted into one another, wherein the printed sheets are successively pulled fold first along a conveying path from a stack of printed sheets by a gripping unit of a feeder and are subsequently gathered with their flat sides placed against each other into book blocks. The gripping unit which grasps the printed sheets approximately at the fold thereof produces a deformation or injury which extends at least partially through the quarto sheets, so that the respective quarto sheets are secured relative to each other and displacements relative to each other are prevented.