Abstract: A binding system is disclosed for binding volumes comprising a cabinet having a trough herein for the receipt of an edge of a stack of sheets with power compressor means on one side of the trough for compressing the stack of sheets and power operated stapling means on the opposite side of the trough for driving staples through the major plane of said sheets adjacent said one edge while under compression. The cabinet also includes a second power operated stapler for binding smaller or thinner stacks of sheets to produce thinner volumes. An interlock provides that only one of the two power operated staplers may be used at a time. Provision is made for loading the larger of said power staplers through the top of the cabinet and a safety mechanism is provided to insure against ejection of staples from the magazine upward through the loading entryway.