The development of a health status measure, the Sickness Impact Profile (SIP), is described in terms of both its conceptualization and methodology. The need for a health status measure that is sensitive and appropriate, based on sickness-related behavior, and culturally unbiased, is discussed. A model of sickness behavior is presented as a guide for methodological development. The description of the initial developmental stage of the SIP includeds detailed discussion and documentation of the collection, sorting and grouping of items that comprise the SIP, scaling of the items, scoring of the instrument, and testing and revision of the prototype instrument. Results of preliminary tests of reliability, validity, and administrative feasibility are presented. Subsequent steps in revision and finalization, now under way, are outlined.