An upper body harness portion for converting a seat-style harness to a full body harness. The upper body harness portion includes a front lower component, a rear lower component, and an upper torso component having elongated first, second and third webbings. The ends of the first and second webbings are detachably securable to opposite sides of the front and rear or side portions of the seat-style harness waist belt, respectively. The third webbing forms a closed loop which, when worn, extends over a wearer's shoulders on opposite sides of the wearer's head. First and second connectors are slidably connected to the third webbing, with the first connector also being slidably connected to the first webbing adjacent the front of a wearer and the second connector being slidably connected to the second webbing adjacent the back of a wearer.