The development, testing, and applicability of an instrument, the Life Activities Questionnaire for Adult Asthma is described that can be used to assess activity restriction in adults with asthma. It explains how items for the instrument were selected to insure the validity of the developed instrument. The reliability of the questionnaire is also discussed. The result is a valid and reliable paper-and-pencil instrument that should have wide applicability as a component of quality of life measurement. This instrument has potential for functional use in clinical settings, research environments, and policy-making procedures.