Abstract: A chair comprises a base, a seat support frame which is longitudinally movable back and forth with respect to said base, and a seat. A lift mechanism mounts the seat on the frame and is capable of lifting said seat from a lowered seating position to a raised position to assist an occupant in exiting from the seat. Locking means is actuatable as the seat is raised to lock the frame against movement with respect to said base. The locking means is released as the seat is lowered to its seating position to free the frame for movement with respect to said base.