Abstract: A platform accessory (20) for use with a straight ladder (22) includes a flat deck (40) adapted both to engage a lower rung (26L) of the ladder (22) and to connect to a higher portion of the ladder by a pair of resilient bracket arms (82). Lower portions (86) of the bracket arms are hingedly connected to the deck (40); intermediate portions (88) of the bracket arms (82) wrap around the ladder's side rails (24); and, upper portions (90) of the bracket arms are insertable into apertures formed in the side rails (24). In one embodiment, apertures (32) in the side rails (24) communicate with interior portions of hollow rungs.