Abstract: An extendable and retractable step for high clearance vehicles. The step is pivotally mounted enabling movement from a retracted, or concealed position, that is, one in which the step is stored beneath the sill of the vehicle door and adjacent the vehicle underbody, to an extended, or revealed position in which the step is projected outward and downward to provide access to the vehicle sill. The step has a positive bracing, or latching, means for assuring against undesired shifting of the step while it is in an extended position. The step unit, or assembly, includes a control system providing a means for moving the step unit from one position to the other and an indicating means to inform the vehicle operator of the step position.