This document, approved by the Rehabilitation Engineering & Assistive Technology Society of North America (RESNA) Board of Directors in September 2005, shares typical clinical applications and provides evidence from the literature supporting the use of seat-elevating devices for wheelchair users. Wheelchair mobility is often only considered from the perspective of people moving from one point to another on a two-dimensional plane (Arva & Schmeler, 2004). Vertical movement is necessary in order for people to function and participate in a three-dimensional world. A common intervention that provides vertical mobility within a wheelchair is a seat-elevating device. It is RESNA's position that seat elevators are often medically necessary to assist individuals accomplish mobility-related activities of daily living tasks (MRADLs). A seat elevator will raise and lower users in their seated position through the use of an electromechanical lift system, without changing the seated angles or the seat's angle relative to the ground, in order to provide varying amounts of added vertical access. It is RESNA's position that seat elevators are often medically necessary for wheelchair users by enabling them to reach, improving MRADL abilities, facilitating or enabling transfers, providing peer height at different ages, enhancing independence and productivity, and delaying or preventing pain and secondary complications of the upper extremities.