Abstract: A window frame comprising a sill, a pair of side jambs and a header is provided. The sill, side jambs, and header include coextensive window pane receiving grooves in which the window pane and glazing are received for mounting the window pane in the window frame. The sill and side jambs are of unitary construction. The header is two piece construction to facilitate installation of the window pane in the frame. The header includes a filler strip that releasably retains a window pane in place in the window frame and the filler cooperates with the remainder of the header to form the window pane groove in the header. A method of installing the window pane in the window frame is also provided.