Many children are still restrained in adult belts alone, even though an adult seat belt is not optimal for small occupants for whom a child restraint would be safer and more desirable. Therefore, a test program was designed to investigate the impact responses of three dummies representing children aged 18 months, three years and six years. The simulations were sled runs at a delta-V of 48 km/h with accelerations of 27 g. The dummies were restrained in adult lap/shoulder, lap-only and child harness belt systems.Neck shear, axial tension and bending moments were rather higher with a lap/shoulder than a lap-only belt. However, the lap/shoulder system minimised dummy head and upper torso excursion, head acceleration and pelvic accelerations.Lap belt loads, head accelerations, HIC and chest accelerations were higher with the lap belt alone than with the lap/shoulder belt. The lap belt also permitted considerable excursion and head contact with the hard frame of the test seat, which affected HIC and neck loads. The lap/harness system gave generally the highest head and neck forces.