The kind of work the person was doing at a job or business during the reference week or, if not at work, at the most recent job or business if employed since 1975. Persons working at more than one job were instructed to describe the one at which the person worked the most hours during the reference week. Occupation is most frequently tabulated for employed persons 16 years old and over, and less often for the experienced civilian labor force, which includes both employed and experienced unemployed 16 years old and over. Occupation data were also collected but are not tabulated for persons not currently in the labor force who have worked since 1975. Occupation is not determined for persons in the Armed Forces. These data were collected on a sample basis.

The write-in responses to questions 29a and 29b were taken together to assign the respondent to one of 503 occupation categories, coded by specially trained industry and occupation coders in census processing offices. Only the code, i.e., none of the written-in information, is retained on census basic records and public-use microdata. Census occupation categories are fully defined in the Classified Index of Industries and Occupations, PHC80-R3. (Persons wishing to use the census system in coding other data bases may use the Alphabetical Index of Industries and Occupations, PHC80-R4.)