The primary aim of this randomized clinical trial is to evaluate whether a standardized modified Burch colposuspension, when added to planned abdominal sacrocolpopexy for the treatment of pelvic organ prolapse, improves the rate of urinary stress continence in subjects without preoperative symptoms of stress urinary incontinence. Secondary aims include comparison of immediate and short-term complications, overall urinary tract function, and other aspects of pelvic health between subjects with and without a concomitant Burch. The value of preoperative urodynamic testing with prolapse reduction will also be compared between subjects with and without a concomitant Burch. This trial is performed through the Pelvic Floor Disorders Network, which is funded by the National Institutes of Health-National Institute of Child Health and Human Development. Subjects will be enrolled at seven clinical centers across the United States and data will be analyzed by the central data coordinating center. Standardized questionnaires and physical observations and measurements will be obtained. The surgical team is masked to the preoperative urodynamic findings, and the patient and research coordinator are masked to treatment assignment. The primary outcome will be determined at 3 months after surgery. Stress continence is defined as absence of stress incontinence symptoms by questionnaire, a negative standardized stress test, and no treatment for stress incontinence other than the study intervention. Additional follow-up occurs at 6, 12, and 24 months. Accrual began in April 2002 and is projected to take 3 years. As of March 6, 2003, 91 patients have been randomized. This article highlights the scientific aspects of trial design for this pivotal clinical trial. The optimal approach to the urinary tract in women treated surgically for prolapse is not known. This trial is designed to provide pelvic surgeons and their patients with scientific data regarding the utility of urodynamics with and without prolapse reduction and the role of colposuspension with sacrocolpopexy. © 2003 Elsevier Inc. All rights reserved.