The Asthma Control Questionnaire (ACQ) has been validated in adults to measure the primary goal of management (minimisation of symptoms, activity limitations, short-acting β₂-agonist use and airway narrowing). The present study evaluated the validity, measurement properties and interpretability of the ACQ in children aged 6-16 yrs. 35 children attended clinic on three occasions (0, 1 and 4 weeks) and completed the ACQ, Mini Paediatric Asthma Quality of Life Questionnaire and the Royal College of Physicians' "Three Questions". Parents completed the Paediatric Asthma Caregiver's Quality of Life Questionnaire. Between visits, children completed the Asthma Control Diary and measured peak expiratory flow. At weeks 1 and 4, clinicians and parents completed Global Rating of Change Questionnaires. All patients completed the study. 19 children were stable between two assessments and provided evidence of good test-retest reliability (intraclass correlation coefficient 0.79). The ACQ was responsive to change in asthma control (p = 0.026) and the mean ± sd Minimal Important Difference was 0.52 ± 0.45. Both cross-sectional and longitudinal correlations between the ACQ and the other outcomes were close to predicted and provided evidence that the ACQ measures asthma control in children. The ACQ has strong measurement properties and is valid for use in children aged 6-16 yrs. In children aged 6-10 yrs, it must be administered by a trained interviewer.