Abstract: An electric machine which can be operated optionally as a motor or generator and in particular can be installed in the drive train of a motor vehicle with a hybrid drive. The machine includes a stator and a rotor of substantially cylindrical shape, The rotor is positioned about the stator to form a circumferential air gap between the stator and the rotor. An integrated switchable clutch is provided for the transmission of torque. The rotor is arranged on the outside (external-rotor machine) of the stator and the clutch is arranged within the stator.