OBJECTIVE: To examine the relationship between magnitude of weight loss and changes in urinary incontinence frequency. METHODS: Overweight and obese women (N=338) with 10 or more urinary incontinence episodes per week were assigned randomly to an intensive 6-month behavioral weight loss program followed immediately by a 12-month weight maintenance program (intervention; n=226) or to a structured education program (control; n=112). The intervention and control groups were combined to examine the effects of the magnitude of weight loss on changes in urinary incontinence assessed by 7-day voiding diary, pad test, and self-reported satisfaction with change in urinary incontinence. RESULTS: Compared with participants who gained weight (reference), those who lost 5% to less than 10% or 10% or more of their body weight had significantly greater percent reductions in urinary incontinence episodes and were more likely to achieve at least a 70% reduction in the frequency of total and urge urinary incontinence episodes at 6, 12, and 18 months. Satisfaction was also related to magnitude of weight loss; approximately 75% of women who lost 5% to less than 10% of their body weight reported being moderately or very satisfied with their changes in urine leakage. CONCLUSION: Weight losses between 5% and 10% of body weight were sufficient for significant urinary incontinence benefits. Thus, weight loss should be considered as initial treatment for incontinence in overweight and obese women. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00091988. LEVEL OF EVIDENCE: II.