Abstract: A trim assembly for interior walls of buildings has a cornerpiece configured for retention in a corner between intersecting walls, a trim strip extending from each opposite side of the cornerpiece, a tang extending from each opposite side of the cornerpiece and extending into slots in respective trim strips, a block member at each opposite side of the cornerpiece, at least one post extending from at least one of the block members and into a slot in a decorative member, and a clip device disposed about the post to retain it in the slot to retain the decorative member relative to the block member.