Abstract: A tilt-in/tilt-out window assembly with improved weather seal gasket includes a pivot bar having a particular cross-section and being integral with the lower frame member of the window sash. The pivot bar is adapted to be received in an aperture of a rotatable disk for pivotal movement within an adjacently opposing shoe integral with a channel formed in an adjacent jamb of the window assembly. A weather seal gasket, positioned on and entirely surrounding the pivot bar between the shoe of the jamb and the sash, includes a centrally located aperture therethrough having a configuration shaped to that of the pivot bar cross-section and a diameter or width at least equal to width of the channel opposing formed in the jamb. The gasket is adapted to seal the junction between the pivot bar and the shoe, thereby preventing the "chimney effect" and thereby improving insulation.