Patients’ self-management of their asthma is a behavioural process. The two most important behaviours are compliance with preventative medication and response to deterioration. It is felt that an understanding of patients’ beliefs about asthma and their attitudes to its treatment should lead to the development of more appropriate and more effective management programmes. However, existing studies suggest that there is little correlation between patients’stated level of beliefs and attitudes to their health and the way in which they actually behave. It is argued that the behaviour of asthmatic patients when treating themselves should be studied using techniques that measure the way in which they make decisions concerning their therapy. This project will identify the possible cues (such as symptoms or effects of asthma) that patients say they use when making judgements concerning changes to their symptomatic and preventative therapy. The use of these cues will then be tested, to examine the way in which they are actually employed by patients when making such judgements. Judgement Analysis techniques will be used to measure the importance of each cue and the manner in which it is used. Patterns of decision making and the influence of demographic and disease-related factors upon this process will be studied.