Stress urinary incontinence results from specific damage to the muscles, fascial structures, and nerves of the pelvic floor. Scientific data are accumulating about the nature of each of these injuries. As we begin to define the damage occurring in each element of the continence mechanism, we should be able to precisely select treatment plans on the basis of the abnormality found in individual patients. For example, a woman who has lost all neural control of her pelvic muscles could be saved the useless frustration of attempting pelvic muscle strengthening, whereas a woman with intact but weak muscles can be made continent with exercise. Before these advances can be realized, we must change our current empiric approach that assigns women to treatment because they have stress urinary incontinence to one that asks about the status of each part of the continence mechanism.