A chair that provides movement side-to-side about a first pivot axis positioned above the seat plane allows the user a wide range of dynamic movement, but does not require constant or excessive action on the part of the user to maintain a desired position. In addition and concurrently thereto, the structure may include a second pivot that is also positioned above the seat plane and that provides forward-and-back movement of the seat. The first and second pivot axes can be engaged synchronously or independently by the user as desired delivering infinite degrees of angles of movement. Said pivot axes are more closely adjacent to the human body pivot joints and axes. The seat and seat back may be joined together to a central spine frame that moves about the second pivot, thereby maintaining the seatback position and seat position relative to each other during forward-and-back movement of the spine along the second pivot. One or more biasing structures may be provided to urge the seat into forward-and-back and side-to-side neutral positions. If desired, the location of this forward-and-back neutral position can be statically adjusted by a user, and at least one of the biasing structures can hold this forward-and-back neutral position at a desired tension level thereby allowing a user to select the amount of force required to move the seat out of this defined forward-and-back neutral position. Moreover, an adjustment structure may be provided that allows for static adjustment of the seatback's position on the spine.