OBJECTIVES: The Asthma Control Questionnaire (ACQ) was developed and validated to measure the adequacy of asthma control in patients 11-70 years. Since younger children may have difficulty reading and understanding the instructions, questions and response options, an interviewer version (ACQ-IA) for 6-10 year old patients was developed and validated in UK English. If children had difficulty understanding an ACQ question, standardised alternative wording was added (in UK English, alternatives were needed for questions 2-4 and 6). The objective was to develop the ACQ-IA in a further 11 languages [English (Australia), French (Belgium), Korean, Norwegian, Portuguese (Brazil, Portugal), Spanish (Argentina, Guatemala, Peru and the USA), and Swedish] based on the adult ACQ versions, using the methodology developed for the UK ACQ-IA. METHODS: First, the concept of each question was defined. For each language there was: (1) forward/backward translation of ACQ-IA instructions; (2) testing of instructions with interviewers; (3) Cognitive interviews with children (6-10yr) with symptomatic asthma (n=5) to identify questions difficult to comprehend; (4) Development of alternative wording for these questions; (5) Testing of the alternatives on a different sample of children (n=5). RESULTS: In all languages at least three questions required alternative wording. Most frequently children had problems understanding medical terms such as “asthma,” “symptoms,” “wheeze,” and “short-acting bronchodilator.” “Asthma” was usually replaced by “difficulty in breathing” and “symptoms” was followed by examples in brackets (hard to breathe, cough, wheeze). For “wheeze”, “whistling sound when you breathe” was the most common alternative. Children usually know their “short-acting bronchodilator” as their “rescue” or “emergency” medicine. CONCLUSIONS: Cognitive interviews with children were crucial for identifying ACQ questions difficult for 6-10 year olds to understand and for formulating the alternative wording in each language. The validity of this novel methodology for the ACQ-IA cultural adaptation has been further supported by these successful adaptations.