A device for opening and closing a movable window of a motor vehicle, the movable window being movable relative to a fixed panel, from a closed position in which the movable window is positioned flush with the fixed panel, to an open position in which the movable window is moved parallel to the fixed panel. The device includes an assembly controlled from a handle mechanism supported by an edge of a frame secured to the movable window, such that starting from the closed position, actuating the handle a first time releases locking of the movable window then, secondly, brings the movable window out of its closed position, an edge of the window corresponding to the edge of the frame being moved relative to the fixed panel, to the position allowing sliding of the movable window.