Abstract: An interior trim system comprising two-piece baseboards, baseboard end caps, window and door casings, crown moldings and window sill caps, the baseboards and crown molding formed with pre-mitered inside and outside corner pieces. The baseboards, end caps, casings and window sill caps can be installed over existing baseboards, casings and window sills without removing the original trim, and are glued into place with instant-hold glue. A template for accurately cutting the window sill cap is included in the system along with a miter guide provided for accurately cutting lengths of baseboards, casings, and crown molding.