The essential aims of this study are to assess the separate and interactive effects of illness severity, job characteristics, psycho-social variables, and other factors on productivity, wage loss, and work disability among adults with asthma. Within this context, asthma stands out as being common and costly among adults at peak ages of labor force participation. The risk factors for adverse impacts of the factors promoting better occupational outcomes are not well delineated. In addition to illness severity, demographic, and psycho-social factors, the nature of working conditions (work exposures, physical demands, job structure) have an impact on work disability. This study therefore addresses a significant research gap identified in the National Occupational Research Agenda (NORA). A random sample of pulmonary and allergy internist specialist initially enrolled 601 persons with asthma identified in patient visit logs. This established panel has completed 45 minute baseline and follow-up computer-assisted telephone interviews. A supplemental sampling frame of persons with asthma identified from family practitioners is in progress (target baseline n=180). The interviews assess disease severity and other co-variables using established survey instruments; work factors are assessed both by interview and by linking to established job factor matrix schemes. The proposed study will carry out extended longitudinal follow-up study of this cohort. The analysis will test predictive models for productivity and wage loss and work disability among adults with asthma. It is anticipated that the proposed study will provide statistically powerful estimates of the occupational impacts of asthma among adults of working age and the factors which are associated with productivity, wage and work loss.