ABSTRACT: Despite the wide use of offloading orthotic devices in orthopedic and neurologic populations, their influence on postural control has received little attention. We, therefore, tested the hypotheses that a nonpneumatic walking boot (WB) increases body motion during balance tests and that adding a heel lift to the noninvolved limb reduces body motion when wearing a WB by correcting the leg length discrepancy. Twelve healthy subjects performed three different types of balance tests, including quiet stance (eyes open or closed, firm or foam surface), functional reach (anterior or lateral directions), and treadmill walking (unperturbed or perturbed). Perturbed walking was used to specifically challenge balance and was created with a treadmill mounted to a continuously rotating platform at 0.5 and 1.5 Hz. In each condition, subjects wore either athletic shoes (control) or a WB covering the lower leg or a WB with heel lift in the opposite shoe. Frontal and sagittal plane upper- and lower-body motion was measured with tilt sensors. The WB significantly increased root-mean-square body motion in quiet stance and walking conditions and significantly decreased anterior functional reach. Body motion with the heel lift was significantly reduced compared with the WB in quiet stance conditions but was similar to the WB in functional reach and walking. Results suggest that the WB influenced balance across all tests by increasing body motion, but the contributing factors (leg length discrepancy, reduced ankle range of motion, or reduced base of support because of the rocker bottom) differed across test conditions. These conclusions add to our understanding of how an offloading orthotic device impacts balance.