Posture-responsive therapy is delivered by the medical system based on posture state input from only one of multiple posture sensors at any given time. An example implantable medical system includes a first posture sensor and a second sensor. A processor controls therapy delivery to the patient based on at least one of a patient posture state or a patient activity level determined based on input from only one of the first or second posture sensors. In some examples, one of multiple posture sensors of an implantable posture-responsive medical system is used to automatically reorient another posture sensor (of the system), which has become disoriented. The disoriented posture sensor may be automatically reoriented for one or more posture states at a time.