Child safety seat

A child safety seat comprising a seat body (10) having a seat portion (12), a seat back (18) and vertically extending side walls (14, 16) projecting forwardly from the side edges of the seat back (18) and upwardly from the side edges of the seat portion (12). The side walls (14, 16) have belt guide openings (20) adjacent to the junction between the seat portion (12) and the seat back (18) for receiving the lap portion (24) of a vehicle seat belt. Respective access slot (22) extends from each belt guide opening (20) to the edge of the corresponding side wall (14, 16). A harness comprising shoulder straps (30, 32) is secured to the seat back (18). The seat body (10, 60, 70, 90) is adapted to deform so that the side walls of each access slot (22) come into abutment with one another when a force is applied to the seat back (18) in a direction to bend it towards the seat portion (12).