Guidelines for the treatment of asthma have identified that the primary goal of management is achieving good asthma control, thus reducing the risk of exacerbations. Research has shown, however, that the accuracy with which clinicians can estimate the adequacy of control may not be very good. Nor are clinicians accurate in estimating change in asthma control between clinic visits. Simple questionnaires to measure asthma control are now available, and can be used to evaluate the adequacy of control and to monitor whether levels of control change between assessments. This article discusses selection of a questionnaire, interpretation of data obtained, and methods of administration.