A method and apparatus for providing a slider-equipped zipper on a pouch in a form/fill/seal operation. In the preferred embodiment of the invention, a foldable slider is employed, and is shifted from an open configuration to a closed configuration for installation on zipper strips on the pouch. Stops are preferably provided at the ends of the zipper strips by application of heat and pressure to form a boss on one side and a corresponding recess on the other, without requiring additional material. A hermetic peelable seal preferably is provided beneath the zipper strips. The slider preferably is applied to the zipper strips immediately before or immediately after filling, or immediately after formation of the peelable seal. Means may be provided to shift the position of the slider to close the zipper. The slider may include means to secure it in place by a mechanical locking mechanism such as a snap fit engagement, or the slider may be welded in closed position by application of heat, or by ultrasonic welding. A vacuum engagement mechanism may be employed to separate the walls of the pouch to a predetermined position relative to one another while positioning and closing the slider.