A convertible bed with a moveable sidewall that can collapse from an upright and locked position to be stored underneath a mattress of the bed. The moveable wall includes pins that travel along sliding tracks that have J-shaped slots underneath the mattress during the conversion from open to closed positions. The moveable sidewall is lifted upward and inwardly to disengage the lock and the folds outwardly and downwardly to slide under the mattress for storage.