Objective: The aim of this study was to identify factors associated with urinary incontinence severity at baseline in women undergoing surgery for stress incontinence. Study design: Baseline data were obtained from 650 women (age 28 to 81 years) with stress incontinence participating in a randomized surgical trial. Severity of incontinence was defined by the mean number of incontinence episodes per day recorded in a 3-day bladder diary. The relationships between severity and several baseline variables were examined, including demographics, medical, obstetric, and gynecologic history, body mass index, smoking status, Q-tip displacement, and Pelvic Organ Prolapse Quantification stage (POP-Q). Results: In a multivariable model, severity of incontinence was positively associated with body mass index (P = .0003) and current smoking (P = .01), and negatively associated with prolapse stage (P < .0001) and Q-tip displacement (P = .042). Conclusion: Incontinence severity in a surgical population was independently associated with 2 modifiable factors, obesity and tobacco use, as well as pelvic support. © 2005 Mosby, Inc. All rights reserved.