As stated in Chapter 1, in view of the additional bandwidth requirement which is limited by stroke constraint and saturation of secondary actuators, three-stage actuation systems are thereby proposed to meet the demand of a higher bandwidth. In this chapter, a specific three-stage actuation system is presented and a control strategy is proposed for the three-stage actuation system, which is based on a decoupled master–slave dual-stage control structure [1] combined with a third-stage actuation in parallel format [2]. This control strategy makes it easy to push the servo bandwidth and meet the performance requirement of the overall control loop. Nevertheless, other control configurations for the three-stage actuation systems are also presented and discussed in this chapter.