A swing assembly has a seat with a folding back that locks the swing automatically when the back folds from an upright configuration to a flat configuration so the swing is stable. The swing assembly includes an upper cross bar having two ends, a lower cross bar having two ends and a lateral support attached to each end of the upper cross bar and the lower cross bar, respectively. The swing assembly has a seat with two ends and a back. The back foldably attaches to the seat. A pair of seat supports attached to each end of the seat and moveably attach to a hanging support mounted on the upper cross bar adjacent each lateral support. A lower back support hangs from the seat back to automatically aligns with and lock with the lower cross bar when the swing moves from the upright configuration to the flat configuration.