Abstract: A stapler and related method for use to bind documents are disclosed in which a selective one of a plurality of different size staples all stored within the stapler itself may be selected for dispensing without necessitating the removal of any staples of a non-selected size from the stapler, or reloading the stapler with the selected size of staples. The stapler contains a magazine having a plurality of cassettes into which staples of different sizes are loaded, with the cassettes being located one atop the other in a stacked array of rows of staples. A selector mechanism is used to alternately, selectively allow one of the rows of staples to be fully advanced to the end of the stapler from which the staples are dispensed, with the other rows of staples being actively urged back away from the end of the stapler from which the staples are dispensed to allow a staple from the selected row to be dispensed.