For the 1970 Decennial Census of Population, the industry and occupation classifications used by the Census Bureau have been revised to provide improved classification systems and more detailed information on the industry and occupation of persons. As a result of these revisions, the classification categories for 1970 and earlier censuses are not strictly comparable. This report is designed to aid data-users in comparing 1960 and 1970 census data by quantifying the interrelationships between the two systems.