According to the present invention there is provided a supplemental restraint harness for cooperating with a seat belt of a vehicle, the supplemental restraint harness comprising, an upper portion which is configured to be worn on the torso of a wearer, wherein the upper portion comprises a first strap which, when the harness is worn, extends along a front of the wearer's torso, over a first shoulder of the wearer, and along a back of the wearer's torso, and a second strap which, when the harness is worn, extends along a front of the wearer's torso, over a second shoulder of the wearer, and along a back of the wearer's torso; and a lower portion, comprising a third strap which can be arranged to form a first loop which can receive a first leg of the wearer, and a fourth strap which can be arranged to form a second loop which can receive a second leg of the wearer; and wherein the upper position and lower portion are connected to one another; and wherein the harness further comprises at least one connector which is suitable for connecting to a seat belt of a vehicle. There is further provided a seat belt assembly which comprises said supplemental restraint harness.