Abstract: A powered lawn mower having a frame, an engine mounted to the frame, a set of front wheels and rear wheels connected to the frame, a drive for transmitting rotational power from the engine to the rear wheels, and grass cutting blades associated with the frame, and powered by the engine. A platform is positioned behind the rear wheels, and is capable of supporting an operator while the lawn mower is operating. The platform and the other parts are connected to the frame in such a way and positioned so that the addition of the operator in a stand-up or riding position moves the center of gravity by no more than twenty-five percent of the wheelbase of the mower. The rear wheel set may be positioned up or down but is not swingable.