Disability among those with asthma is common and costly. Little is known about the causes of disability in asthma; experience with other chronic diseases suggests that illness severity alone does not adequately predict disability. There is a theoretical and experimental basis upon which to postulate that other variables, including factors such as job flexibility, asthma self-efficacy, social supports, and cigarette smoking may be predictors of disability in asthma. The study helped to explain the inter-relationships among illness severity, other co-factors and disability in asthma, addressing a major research gap.