Several reviewers have recently identified a need for systematic efforts to improve the quality of questionnaires and other measures used in asthma research. This article applies standard psychometric techniques to scales developed to help meet this need. These scales assess asthma symptoms, respiratory diseases, the extent to which asthma inconveniences patients, medication regimens, and medication side effects. Scale quality was assessed by using data from 262 adult asthma patients. The results in general support the usefulness of these scales. The reliabilities indicate an acceptable to good level of internal consistency; the spread of scores is good; and correlations with external variables support validity.