A rotatable seat cradle (1) including a lumbar supporting back (3), a thigh supporting front (5), an intermediate pelvic support bucket (7) located between the back and the front, and an upwardly sloping transition wall (23) that extends continuously and co-extensively between the pelvic support bucket (7) and the thigh supporting front (5). The seat cradle (1) is pivotally coupled to a stand (16) or to a yoke (50) connected to a chair base (72). The thigh supporting front (5) of the seat cradle (1) lies above the pelvic support bucket (7) and cantilevers outwardly from the upwardly sloping transition wall (23). A seated user shifting his weight towards the front (5) of the seat cradle (1) pushes his legs against the thigh supporting front to generate a rotational force thereagainst for causing a corresponding rotation of the seat cradle (1) relative to the stand (16) or the yoke (50) to which the seat cradle is pivotally coupled.
