Background. A reliable method of documenting the frequency of incontinent episodes is essential for assessment of treatment outcome in both clinical practice and research studies. Bladder diaries, completed prospectively by the patient, have been widely used for this purpose. This study investigated the number of consecutive days of bladder diary reports of incontinence frequency necessary to obtain adequate internal consistency (reliability). Methods. Participants were 214 community-dwelling women, aged 40 to 90 years, with a history of stress, urge, or mixed urinary incontinence, persisting at least 3 months with a frequency of two or more episodes of urine leakage per week. Each participant kept a 14-day bladder diary documenting the time and circumstances of each incontinence episode. Results. The mean age of participants was 63.5 years; 16.9% were African American. Women with predominantly urge incontinence (n = 138) reported a daily frequency of 2.1 incontinent episodes. Although there was a statistically significant difference between Week 1 (2.4 episodes per day) and Week 2 (2.0 episodes per day; p < .0001), five days were necessary to obtain an internal consistency of .90 for Cronbach's alpha. Women with predominantly stress incontinence (n = 76) had no statistical difference between Week 1 and Week 2 in frequency of incontinence, reporting an average 2.2 accidents per week in Week 1 and 2.1 in Week 2. However, 7 days of bladder diary were required before adequate internal consistency was reached. Conclusion. Seven consecutive days of bladder diary provides a stable and reliable measurement of the frequency of incontinence episodes in community-dwelling women.