To develop and evaluate the International Consultation on Incontinence Questionnaire (ICIQ), a new questionnaire to assess urinary incontinence and its impact on quality of life (QoL). A developmental version of the questionnaire was produced following systematic literature review and views of an expert committee and patients. Several studies were undertaken to evaluate the psychometric properties of the questionnaire, including content, construct and convergent validity, reliability and sensitivity to change. The ICIQ was easily completed, with low levels of missing data (mean 1.6%). It was able to discriminate among different groups of individuals, indicating good construct validity. Convergent validity was acceptable, with most items demonstrating 'moderate' to 'strong' agreement with other questionnaires. Reliability was good, with 'moderate' to 'very good' stability in test-retest analysis and a Cronbach's alpha of 0.95. Items identified statistically significant reductions in symptoms from baseline following surgical and conservative treatment. Item reduction techniques were used to determine the final version and scoring scheme, which also demonstrated good psychometric properties. The final ICIQ comprises three scored items and an unscored self-diagnostic item. It allows the assessment of the prevalence, frequency, and perceived cause of urinary incontinence, and its impact on everyday life. The ICIQ is a brief and robust questionnaire that will be of use in outcomes and epidemiological research as well as routine clinical practice. Copyright 2004 Wiley-Liss, Inc.