A drive system having an integrated transmission and motor/generator unit for a wind turbine includes a transmission output shaft designed as a hollow shaft, which receives a sun shaft of an output-side planetary gear stage and is connected thereto. The transmission output shaft comprises a transmission-side end section of an insert shaft which is concentrically arranged within a rotor hollow shaft. The transmission output shaft additionally has a bearing for receiving radial and axial forces. The motor/generator unit has two dedicated bearings. One bearing thereof is a transmission-side bearing. In addition, a rear-side generator bearing is provided.