Abstract: An attitude control system for a stabilized geostationary satellite comprising at least one terrestrial detector (T.sub.1) and a stellar detector oriented towards the North further comprises:a processing subsystem for each of at least the normal mode (I) and the stationkeeping mode (II), adapted to be connected to the detectors and to actuators (11, 12, 13) and comprising a pre-processing module (14-16) adapted to determine for each axis i an angular offset .epsilon..sub.i between a measured angle determined from the detectors and a reference angle together with a control and correction module (18, 20) adapted to determine for each axis a corrective torque of the form:c=k.sub.i..epsilon..sub.i +h.sub.i..epsilon..sub.iwhere k.sub.i and h.sub.i are parameters specific to each axis and to each processing line,a speed .epsilon..sub.i measuring unit (24,25),and a mode selection unit (26) connecting the detectors to a selected processing line and that processing line to at least one actuator.