The International Standard Classification of Occupations- ISCO-08

ISCO-08 is a four-level hierarchically structured classification that allows all jobs in the world to be classified into 436 unit groups. These groups form the most detailed level of the classification structure and are aggregated into 130 minor groups, 43 sub-major groups and 10 major groups, based on their similarity in terms of the skill level and skill specialization required for the jobs.

ISCO-08 was adopted through a resolution of a Tripartite Meeting of Experts on Labour Statistics held in December 2007. This resolution was subsequently endorsed by the Governing Body of the International Labour Organization in March 2008. ISCO-08 is the fourth iteration and replaces previous versions of ISCO.

Major definitions and concepts used in ISCO-08

  • A job is defined as “a set of tasks and duties performed, or meant to be performed, by one person, including for an employer or in self employment”.
  • Occupation refers to the kind of work performed in a job. The concept of occupation is defined as a “set of jobs whose main tasks and duties are characterized by a high degree of similarity”. A person may be associated with an occupation through the main job currently held, a second job, a future job or a job previously held.
  • Skill is the ability to carry out the tasks and duties of a job.

Structure and composition of ISCO-08

Looking at the hierarchical structure of ISCO-08 from the top down, each of the ten major groups is made up of two or more sub-major groups, which in turn are made up of one or more minor groups. Each of the 130 minor groups is made up of one or more unit groups. In general, each unit group is made up of several “occupations” that have a high degree of similarity in terms of skill level and skill specialization.

Each group in the classification is designated by a title and code number and is associated with a description that specifies the scope of the group.

  • Major Group is denoted by a 1-digit code, example 2 Professionals
  • Sub-Major Group is denoted by a 2-digit codes, example 22 Health Professionals
  • Minor Groups are denoted by 3-digit codes, example 221 Medical doctors
  • Unit Groups are denoted by 4-digit codes, example 2211 Generalist Medical Practitioners



ISCO-08 Number of groups at each level and skill levels

(Download ISCO-08 Structure and definitions for all groups in Excel)

Major Groups Sub Major Groups Minor Groups Unit Groups Skill level
1 Managers 4 11 31 3 and 4
2 Professionals 6 27 92 4
3 Technicians and Associate Professionals 5 20 84 3
4 Clerical Support Workers 4 8 29 2
5 Service and Sales Workers 4 13 40 2
6 Skilled Agricultural, Forestry and Fishery Workers 3 9 18 2
7 Craft and Related Trades Workers 5 14 66 2
8 Plant and Machine Operators, and Assemblers 3 14 40 2
9 Elementary Occupations 6 11 33 2
0 Armed Forces Occupations 3 3 3 1, 2 and 4
Total number of groups 43 130 436

ISCO-08 Skill model in brief

For the purposes of ISCO-08, two dimensions of skill are used to arrange occupations into groups, these are skill level and skill specialization.

Skill level is defined as a function of the complexity and range of tasks and duties to be performed in an occupation. Skill level is measured operationally by considering one or more of:

  • the nature of the work performed in an occupation in relation to the characteristic tasks and duties defined for each ISCO-08 skill level;
  • the level of formal education defined in terms of the International Standard Classification of Education (ISCED-97) required for competent performance of the tasks and duties involved; and
  • the amount of informal on-the-job training and/or previous experience in a related occupation required for competent performance of these tasks and duties.

Normally skill level is applied at the level of ISCO Major Groups, with the exception in Major Group 1: Managers, and Major Group 0: Armed Forces Occupations, where the concept of skill level is applied primarily at the second hierarchical level.

There are four skills levels in ISCO-08 and they are defined in details and provides examples of:

  • the typical or characteristic tasks performed at each skill level;
  • the types of skill required (in broad terms); and
  • the typical occupations classified at that skill level.
Mapping of the four ISCO-08 skill levels to ISCED-97 levels of education
ISCO-08 skill level ISCED-97 groups
4 6 Second stage of tertiary education (leading to an advanced research qualification)
4 5a First stage of tertiary education, 1st degree (medium duration)
3 5b First stage of tertiary education (short or medium duration)
2 4 Post-secondary, non-tertiary education
2 3 Upper secondary level of education
2 2 Lower secondary level of education
1 1 Primary level of education

Skill specialization is considered in terms of the four concepts:

  • the field of knowledge required;
  • the tools and machinery used;
  • the materials worked on or with; and
  • the kinds of goods and services produced.

Within each major group, occupations are arranged into unit groups, minor groups and sub-major groups, primarily on the basis of aspects of skill specialization.

Browse ISCO-08

Browsing ISCO-08 structure with search function allowing you to navigate between the different groups. Click here to start .

Download ISCO-08 material

Material Description
ISCO-08 Volume 1 ISCO-08 methodological notes, history, structure, group definition, description of tasks and duties, examples of occupations, correspondence table with ISCO-88 etc, in Pdf
Structure and group definitions ISCO-08 structure, group definition, description of tasks and duties, examples of occupations, in Excel
Index of Occupational Titles List containing occupational titles used in ISCO-08, in Excel
Skills Description of skills used in ISCO-08, in Excel
ISCO structure in CSV format ISCO structure in CSV format