The purpose of this study was to quantify the limits of stability of wheelchair users across a functional spectrum. Eight manual wheelchair users completed a seated limits of stability test to determine maximum range of motion of their trunk forward, backward, right, left, and rotation of the trunk. The low functional classification group had significantly less trunk excursion than the high functional classification group for trunk flexion, rotation, and left and right lateral flexion. Wheelchair basketball players in lower functional classifications have a lower capacity to control their trunk excursion in lateral, anterior, and posterior directions, as well as rotation. These results lend support to the validity of the functional classification system used in wheelchair basketball.