There is disclosed a single hung aluminum window in which the sash is provided with plastic inserts in its stiles at their upper and lower ends, such inserts having portions which serve as guide and spacer members which bear against the jambs of the frame in which the stiles are positioned. The inserts also form housings which include respective pushbuttons and bias springs, the buttons extending through aligned openings in such housings and the inner stile faces. In the head portion of the frame are elongated stop members adapted to be swiveled between vertical and horizontal positions, and which in vertical positions prevent upward movement of the sash beyond the point wherein it is not engaged by the feet of the balance mechanisms mounted in the jambs. When it is desired to remove the sash from the frame, the stop members are moved to horizontal positions to permit the sash to be moved upward sufficiently so that its lower end clears the feet of the balance mechanisms, such feet being captured by clips secured in the jambs. With the sash thus disengaged from the balance mechanisms, its removal is effected by depressing the pushbuttons of one stile to clear the adjacent jamb wall as the sash is moved laterally into such jamb, and the opposite stile clears the opposite jamb and can be swung free to permit the sash to be pulled free of the frame.