Abstract: A folding step ladder of multipart construction that is extendable from a standard base height to a series of heights incrementally greater than the standard base height, and that is composed of four ladder elements; an upper-front element joined to an upper-rear element at a top hinge-step, a lower-front element slidingly joined to the upper-front element along its length, and a lower-rear element slidingly joined to the upper-rear element along its length. The lower elements captively slide along the length of their corresponding upper element and are capable of being held at a particular incremental extension by a latch arrangement that engages the upper element when downward force is exerted on the ladder.