A wheelchair frame having a seat for supporting a forward facing occupant therein, rear wheels supporting the frame thereon proximate a rear end of the frame and front wheels supporting the frame thereon proximate a front end of the frame, further includes a front seat height adjustment mechanism which permits a height of a front end of the seat relative to the front wheels to be adjusted separately from or together with a rear end height adjustment of the rear end of the seat relative to the rear wheels. The front seat height adjustment mechanism can also be operable to lower the front seat height relative to the front wheels simultaneously with a rear seat height adjustment mechanism which is biased to raise the rear seat height relative to the rear wheels to assist users in moving from a sitting position towards a more standing position.