A vehicle suspension system for controlling motion of a sprung and unsprung mass comprising: a force source which is capable of applying a force in response to a control signal and without a physical stimulus, the force source coupling a vehicle unsprung mass and a vehicle sprung mass: a sensor for detecting vertical motion of the sprung mass or a quantity from which vertical motion of the sprung mass can be derived; an unsprung mass sensor for detecting vertical motion of the unsprung mass or a quantity from which vertical motion of the unsprung mass can be derived; and control circuitry responsive to the sprung mass sensor for determining a force to reduce the vertical motion of the sprung mass in a first frequency range; and responsive to the unsprung mass sensor for determining a force to reduce the vertical motion of the unsprung mass in a second frequency range; wherein the first frequency range includes frequencies above and below the second frequency range and wherein the first frequency range does not include the second frequency range; characterized in that the control circuitry comprises an anti-causal filter; the vehicle suspension system further comprising circuitry for detecting vertical disturbances in the road ahead of a wheel that is a component of the unsprung mass, wherein the wheel is a rear wheel and wherein the circuitry for detecting vertical disturbances in the road is associated with a front wheel; wherein the anti-causal filter is arranged for: determining, prior to the wheel's encountering the road disturbance, an estimated response of the vehicle suspension to the disturbance; reversing with respect to time the estimated response to provide an anti-causal response; and causing the controllable force source to apply the anti-causal response prior to the wheel encountering the road disturbance. a force source which is capable of applying a force in response to a control signal and without a physical stimulus, the force source coupling a vehicle unsprung mass and a vehicle sprung mass: a sensor for detecting vertical motion of the sprung mass or a quantity from which vertical motion of the sprung mass can be derived; an unsprung mass sensor for detecting vertical motion of the unsprung mass or a quantity from which vertical motion of the unsprung mass can be derived; and control circuitry responsive to the sprung mass sensor for determining a force to reduce the vertical motion of the sprung mass in a first frequency range; and responsive to the unsprung mass sensor for determining a force to reduce the vertical motion of the unsprung mass in a second frequency range; a sensor for detecting vertical motion of the sprung mass or a quantity from which vertical motion of the sprung mass can be derived; an unsprung mass sensor for detecting vertical motion of the unsprung mass or a quantity from which vertical motion of the unsprung mass can be derived; and control circuitry responsive to the sprung mass sensor for determining a force to reduce the vertical motion of the sprung mass in a first frequency range; and responsive to the unsprung mass sensor for determining a force to reduce the vertical motion of the unsprung mass in a second frequency range; wherein the first frequency range includes frequencies above and below the second frequency range and wherein the first frequency range does not include the second frequency range; characterized in that the control circuitry comprises an anti-causal filter; the vehicle suspension system further comprising circuitry for detecting vertical disturbances in the road ahead of a wheel that is a component of the unsprung mass, wherein the wheel is a rear wheel and wherein the circuitry for detecting vertical disturbances in the road is associated with a front wheel; wherein the anti-causal filter is arranged for: determining, prior to the wheel's encountering the road disturbance, an estimated response of the vehicle suspension to the disturbance; reversing with respect to time the estimated response to provide an anti-causal response; and causing the controllable force source to apply the anti-causal response prior to the wheel encountering the road disturbance. determining, prior to the wheel's encountering the road disturbance, an estimated response of the vehicle suspension to the disturbance; reversing with respect to time the estimated response to provide an anti-causal response; and causing the controllable force source to apply the anti-causal response prior to the wheel encountering the road disturbance.