BACKGROUND: Cough and sputum are leading symptoms of chronic (obstructive) bronchitis. It is acknowledged that these symptoms impact patients' lives, yet they have never been measured adequately. OBJECTIVE: To develop a self-administered instrument in five countries (seven languages) that captures concepts relevant to chronic (obstructive) bronchitis patients who suffer from cough and sputum. METHODS: After literature review and appraisal of existing instruments, a conceptual model was developed and then reviewed by clinical respiratory experts. Thirty extensive face-to-face concept elicitation interviews were conducted with patients in five countries (France, Germany, Japan, Spain, US). After transcription and domain-mapping of the interviews in each country, an international item generation meeting was conducted and a draft questionnaire was simultaneously created in five languages. After clinical expert review, testing for face and content validity was performed in cognitive debriefings in seven languages in six countries with 35 patients (English for US/UK, French, German, Japanese, Spanish for US/Spain). RESULTS: The conceptual model addressed symptoms of cough and sputum and their respective impact. The resulting questionnaire, Cough and Sputum Assessment Questionnaire (CASA-Q), has 25 items with 6 items for symptoms (3 cough, 3 sputum) and 19 items for the impact of these symptoms (12 cough, 7 sputum). The response choices per item consist of five options from “never” to “always” or “not at all” to “extremely”, depending on the context of the item. Due to its simultaneous item generation in five languages and field testing in seven languages, item wording overall is following a simple sentence structure. The ease of understanding and relevance of each question was found acceptable across languages. CONCLUSION: The CASA-Q is a well-developed, patient-based questionnaire relevant to the assessment of chronic bronchitis. The CASA-Q, after completion of psychometric validation, may contribute to a comprehensive patient-centred assessment.