The International Standard Classification of Occupations (ISCO-88), adopted by the International Conference of Labour Statisticians in 1987 and approved by the International Labour Organisation (ILO) in 1988, provides a system for classifying and presenting occupation information which facilitates international comparison.

The ISCO-88 was first adapted by the Census and Statistics Department for use in the 1991 Population Census (91C). It was then adapted for use in the General Household Survey after the 91C. For each subsequent round of population census and by-census, reference was made to the ISCO-88 for devising the occupation classification adopted.

As the custodian of the ISCO, the ILO has prepared an updated version of the classification, known as ISCO-08. The final draft definitions of ISCO-08 have been uploaded to the ILO website.