A screw cap and sealing liner construction including a cap body having a transverse top wall with an inside surface, and having an annular skirt depending from the top wall, the annular skirt having an internal screw thread which extends upward and has a top end located closely adjacent the inside surface. A sealing liner is disposed immediately below and against the inside wall surface, and has a peripheral portion located between this surface and the top end of the screw thread to be engaged and positioned thereby. A nib is provided on the inside of the annular skirt at a location circumferentially spaced from the top end of the screw thread. The nib is adjacent the inside surface of the top wall and engages the underside of the sealing liner to retain the liner in position below this surface. The arrangement simplifies both the molding of the cap and the stripping of the cured part from the mold.