Vibration Control of Active Structures : An Introduction Some concepts of structural dynamics Actuators piezoelectric materials and active structures Collocated versus non collocated control Active damping with collocated pairs Active vibration isolation State space approach Analysis and synthesis in the frequency domain Optimal control Controllability and Observability Stability Semi active control Applications Tendon Control of Cable Structures. My objective in writing this book was to cross the bridge between the structural dynamics and control communities while providing an overview of the potential of SMART materials for sensing and actuating purposes in active vibration c trol. I wanted to keep it relatively simple and focused on systems which worked. This resulted in the following: (i) I restricted the text to fundamental concepts and left aside most advanced ones (i.e. robust control) whose usefulness had not yet clearly been established for the application at hand. (ii) I promoted the use of collocated actuator sensor pairs whose potential I thought was strongly underestimated by the control community. (iii) I emphasized control laws with guaranteed stability for active damping (the wide ranging applications of the IFF are particularly impressive). (iv) I tried to explain why an accurate pred tion of the transmission zeros (usually called anti resonances by the structural dynamicists) is so important in evaluating the performance of a control system. (v) I emphasized the fact that the open loop zeros are more difficult to predict than the poles and that they could be strongly influenced by the model trun tion (high frequency dynamics) or by local effects (such as membrane strains in piezoelectric shells) especially for nearly collocated distributed actuator sensor pairs; this effect alone explains many disappointments in active control systems.