Abstract: A self-deploying stabilizing support jack is presented which stabilizes and positions a recreational vehicle or trailer. The support jack comprises a bracket, a two-cylinder, lift arms and a stabilizing sleeve. The lift arms and cylinder are attached to the bracket at separate, offset first and second points so that when the ram of the cylinder contacts the foot of the lift arm, the entire apparatus is raised to a horizontal position. A stabilizing sleeve attached to the lift and surrounding the cylinder stabilizes the the device from lateral movement. An intermediate third pivot point in the lift arm helps reduce stress upon raising. Also provided is an automatically released pressure valve for the cylinder and a signalling device to warn the operator when the support jack is in the deployed position. A safety circuit also automatically raises any support jack that is not in the horizontal safety position should the ignition be turned to the "ON" position.