Abstract: A portable ladder having stabilizer brackets slidably mounted on the ladder siderails to permit the ladder to be mounted to a flatbed trailer tiedown rail. The slidable stabilizer brackets are substantially self-adjusting in position, and adjust automatically, for example, when a load is removed from the trailer. The ladder may optionally include two sections pivotably interconnected to facilitate handling and storage. A lock to secure the two sections together in an extended position may also be provided. The advantage is a lightweight, portable ladder which can be used with practically any flatbed trailer. The ladder adjusts substantially automatically to the height of the trailer to provide stable access to the trailer bed.