A new generation of engine mounts has been developed: active mounts. They have all the features of hydraulic engine mounts, plus active vibration control to reach near perfect isolation. This paper gives an in depth description of this new technology.First, the general layout of an active mount is described, and a vibration model is given. Secondly, a new type of actuator had to be developed, with some remarkable features: high power density, energy recovery capability, optimal damping, etc. Then the electronic control unit is described, with the algorithms used.Eventually, measurements on a vehicle in real driving conditions show a dramatic improvement in both vibrational and acoustic comfort, leading the way to industrialization.