An automatic closure assembly for a sliding panel (20), particularly of the screen door type, is disclosed. One or more power springs (40, 41, 42) operable in their linear ranges are mounted within a compact housing (30) configured for ready attachment to a surface adjacent the sliding panel (20). The springs (40, 41, 42) apply tension to a cord (34) wound on a take-up reel (45) within the housing (30). One end of the cord (34) is screwed to the sliding panel (20) such that as the panel is moved in an opening direction, the power spring(s) (40, 41, 42) are wound in tension to apply closure forces to the panel (20). An adjustment is provided for enabling an operator to select a plurality of different discrete tension forces to be applied by the closure assembly to the sliding panel (20).