In this thesis the active control of a vibration neutraliser is considered. In order to adjust the tuned frequency and bandwidth of the device, control of both neutraliser stiffness and damping is required. An impedance-based approach is used to develop a number of damping control configurations. It is found that one of six possible configurations has distinct advantages. Simulation and experimental results in the frequency domain support this conclusion. The variation of stiffness by changing the separation between the two beam elements of a beam-like neutraliser is discussed. Four different separation geometries are considered. Linear approximations between beam separation and tuned frequency are derived. By considering the torque required to separate the beams a preferred configuration is established. Analytical, numerical and experimental results are presented. The control of the damping and stiffness of a neutraliser in the time domain is considered. A simple fuzzy logic controller is used to control the stiffness of the beam-like neutraliser when it is excited by an approximate swept sine wave. Numerical and experimental results are presented which demonstrate that the tuned condition and hence the level of attenuation is maintained. The damping within the neutraliser is controlled using a piezoceramic actuator and a fuzzy logic rule base. Numerical and experimental results show that it is possible to improve upon the passive tuned behaviour. The above two controllers are combined. The simultaneous control of both tuning and damping in a vibration neutraliser subjected to an approximate swept sine wave excitation is demonstrated. Numerical and experimental results are presented.