Abstract: The present invention provides improved window frames and window frame systems for containing slideably mounted window sash systems. The present invention includes guides in upper horizontally oriented window frame heads which are of different depths on left and right horizontal sides, so that window sash systems present can-be slid into a closed position under a shallower guide means wherein they can not be pried upward. The improved window frames and window frame systems can provide self contained wall trim, provide structural integrity, provide improved thermal control, and are easy to install by a convenient, described method. A prefered present invention window frame is of single piece construction and is fabricated by a resin transfer process.