BACKGROUND: Questionnaires assessing accidental bowel leakage lack important patient-centered symptoms. OBJECTIVE: We aimed to create a valid measure of accidental bowel leakage symptoms. DESIGN: We previously created a conceptual framework capturing patient-centered accidental bowel leakage symptoms. The framework included bowel leakage type, severity and bother, and ancillary bowel symptoms, including predictability, awareness, leakage control, emptying disorders, and discomfort. SETTINGS: The study was conducted in outpatient clinics. PATIENTS: Women with at least monthly accidental bowel leakage were included. INTERVENTIONS: Participants completed the Accidental Bowel Leakage Evaluation at baseline and 12 and 24 weeks, as well as bowel diaries and other validated pelvic floor questionnaires. A subset completed items twice before treatment. Final item selection was based on psychometric properties and clinical importance. MAIN OUTCOME MEASURES: Psychometric analyses included Cronbach α, confirmatory factor, and item response theory analyses. Construct validity was based on correlations with measures of similar constructs. RESULTS: A total of 296 women completed baseline items, and 70 provided test-retest data. The cohort was predominately white (79%) and middle aged (64 ± 11 y). Confirmatory factor analyses supported the conceptual framework. The final 18-item scale demonstrated good internal consistency (Cronbach α = 0.77-0.90) and test-retest reliability (intraclass correlation = 0.80). Construct validity was demonstrated with baseline and 12- and 24-week scale scores, which correlated with the Vaizey (r = 0.52, 0.68, and 0.69), Colorectal Anal Distress Inventory (r = 0.54, 0.65, 0.71), Colorectal Anal Impact Questionnaire (r = 0.48, 0.53, 0.53), and hygiene (r = 0.39, 0.43, 0.49) and avoidance subscales scores of the adaptive index (r = 0.45, 0.44, 0.43) and average number of pad changes per day on bowel diaries (r = 0.35, 0.38, 0.31; all p < 0.001). LIMITATIONS: The study was limited by nature of involving validation in a care-seeking population. CONCLUSIONS: The Accidental Bowel Leakage Evaluation instrument is a reliable, patient-centered measure with good validity properties. This instrument improves on currently available measures by adding patient-important domains of predictability, awareness, control, emptying, and discomfort.