The purpose of this study was to examine the ligamentous contributions to pelvic stability. Thirteen fresh frozen cadaver pelves were loaded in an MTS materials testing machine, and the supporting ligaments were sequentially cut. After each ligament was cut, measurements of pelvic stability were made. Pelvic stability was maintained most effectively when the pelvic ring remained intact. The sacrotuberous and sacrospinous ligaments contributed little to overall pelvic stability. The posterior sacroiliac ligament and the pubic symphyseal ligaments contributed most to pelvic stability, but overall it was clear that a ligament's contributions to pelvic stability depended not only on the ligament's size, but also on the other ligament remaining intact and the mode in which the pelvis was loaded.