Abstract: A seat frame comprises a resilient seating platform attached to first, second and third horizontal frame members, the first member being at the front of the seat and at seat level and the second and third members being at the back of the seat and respectively above and below seat level. The resilient platform comprises first sheet means, including a full-width elastic portion, secured along one edge to the first frame member and along an opposite second edge to a second sheet means. The second sheet means comprises a first portion secured along its opposite edges to the second frame member and the second edge of the first sheet means respectively and a second portion secured along its opposite edges to the third frame member and the second edge of the first sheet means respectively.