A scaffold includes a U-profile beam having an outwardly-open U-profile in which a scaffold platform is releasably hooked by mounting hooks. The U-profile beam has a perpendicular wall delimiting the U-profile and a guiding and fastening groove delimited by inwardly-extending groove reach-behind protrusions delimiting a locking space for releasably locking a locking element reaching behind the protrusions. An anti-lift-out and support element has an anti-lift-out element extending over the hooks to prevent lifting out. A support element fixed to the anti-lift-out element extends perpendicularly from the anti-lift-out element to a support element end for supporting the support element on the wall. The anti-lift-out element has a through-opening designed so that the fastening element moves the locking element toward the fastening element longitudinal axis and perpendicularly to the groove through the through-opening. A method secures scaffold platform mounting hooks against lifting out from a U-profile beam using an anti-lift-out device.