Abstract: A latching mechanism for a pair of relatively slidable overlapping window panels includes a pair of opposed fixed support blocks with bearing surfaces engageable with the outside surfaces of the window panels. A first wedging block is floatingly mounted between the window panels and has a bearing surface engageable with the inside surface of one window panel and a slanted wedging surface spaced from the inside surface of the other window panel. A latching lever, movable between operative and inoperative positions, is secured to a second wedging block which has a wedging surface engageable with the wedging surface of the first wedging block and a bearing surface engageable with the inside surface of the other window panel. In the operative position of the lever, the engagement of the wedging surfaces of the wedging blocks engages the bearing surfaces of the wedging blocks with the inside surfaces of respective window panels to wedge the panels against the bearing surfaces of the support blocks.