International Standard Classification of Occupations


The International Standard Classification of Occupations is a system developed by the International Labour Organization to classify and organize occupations into a structured hierarchy. It serves to facilitate international communication about occupations by providing a framework for statisticians to make internationally comparable occupational data available.
The ILO describes the purpose of the ISCO as:
seek to facilitate international communication about occupations by providing statisticians with a framework to make internationally comparable occupational data available, and by allowing international occupational data to be produced in a form that can be useful for research as well as for specific decision-making and action-oriented activities.
According to the ILO, 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, and 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, in this context, is the ability to carry out the tasks and duties of a job.
The latest version, ISCO-08, was adopted in 2008 and includes four classification levels: major groups, sub-major groups, minor groups, and unit groups. It is widely used for comparative labor market studies, policy development, and international reporting, including within the European Union, the United Nations, and other global institutions.

History and development

The origins of ISCO trace back to the mid-20th century when the need for a global occupational classification system became evident at the First International Conference of Labour Statisticians in 1923. The first complete version, ISCO-58, was adopted in 1957 by the Ninth ICLS and published in 1958, providing a systematic method for grouping occupations to support labor market analysis and facilitate international comparisons. Subsequent revisions, including ISCO-68, ISCO-88, and ISCO-08, refined the classification criteria to reflect changing labor market structures, technological advancements, and evolving job roles. Notably, ISCO-88 marked a major departure from the earlier versions by organizing similar occupations into increasingly larger groups based on skill level and specialization.
ISCO has since been widely adopted by national governments and international organizations to align workforce data with global labor market trends. ISCO has been continuously adapted to ensure its relevance amid shifts in employment patterns, technological progress, and the emergence of new economic sectors. Moreover, its role in international labor statistics enables cross-country comparisons, aiding in policy formulation and economic planning.
The ISCO-08 revision was developed through consultations with national governments, labor organizations, and international experts to ensure relevance and adaptability. Key issues addressed in the ISCO-08 revision included the impact of information and communications technology on the labor market's occupational structure, the need for better representation of health organizations, and the lack of detail in ISCO-88 for clerical and service-related occupations, which are predominantly held by women. Looking ahead, future iterations of ISCO are expected to incorporate new occupational categories reflecting automation, digital transformation, and emerging industries.
The adaptation of ISCO-08 for national use is a critical process to ensure its applicability across diverse labor markets. Countries often modify ISCO-08 to align with national occupational classifications while maintaining international comparability. For instance, the European Union, through the European Skills, Competences, Qualifications and Occupations framework, has built upon ISCO-08 by incorporating more detailed competencies and qualifications for cross-border labor mobility. This adaptation process involves mapping national job structures to ISCO categories, refining classifications to reflect local labor market conditions, and ensuring consistency in data reporting for global labor statistics. Of note, Donald Treiman developed the Standard International Occupational Prestige Scale using the ISCO.

The ISCO-08 structure

ISCO-08 organizes occupations into a four-level hierarchical system:
  1. Major Groups
  2. Sub-Major Groups
  3. Minor Groups
  4. Unit Groups
The ISCO-08 divides jobs into 10 major groups:
  1. Managers
  2. Professionals
  3. Technicians and associate professionals
  4. Clerical support workers
  5. Service and sales workers
  6. Skilled agricultural, forestry and fishery workers
  7. Craft related trades workers
  8. Plant and machine operators, and assemblers
  9. Elementary occupations
  10. Armed forces occupations

    Major group 1

Managers
Professionals
Technicians and associate professionals
  • 31 Science and engineering associate professionals
  • *311 Physical and engineering science technicians
  • *312 Mining, manufacturing and construction supervisors
  • *313 Process control technicians
  • *314 Life science technicians and related associate professionals
  • *315 Ship and aircraft controllers and technicians
  • 32 Health associate professionals
  • *321 Medical and pharmaceutical technicians
  • *322 Nursing and midwifery associate professionals
  • *323 Traditional and complementary medicine associate professionals
  • *324 Veterinary technicians and assistants
  • *325 Other health associate professionals
  • 33 Business and administration associate professionals
  • *331 Financial and mathematical associate professionals
  • *332 Sales and purchasing agents and brokers
  • *333 Business services agents
  • *334 Administrative and specialized secretaries
  • *335 Regulatory government associate professionals
  • 34 Legal, social, cultural and related associate professionals
  • *341 Legal, social and religious associate professionals
  • *342 Sports and fitness workers
  • *343 Artistic, cultural and culinary associate professionals
  • 35 Information and communications technicians
  • *351 Information and communications technology operations and user support technicians
  • *352 Telecommunications and broadcasting technicians

    Major group 4

Clerical support workers
  • 41 General and keyboard clerks
  • *411 General office clerks
  • *412 Secretaries
  • *413 Keyboard operators
  • 42 Customer services clerks
  • *421 Tellers, money collectors and related clerks
  • *422 Client information workers
  • 43 Numerical and material recording clerks
  • *431 Numerical clerks
  • *432 Material-recording and transport clerks
  • 44 Other clerical support workers
  • *441 Other clerical support workers

    Major group 5

Service and sales workers
  • 51 Personal service workers
  • *511 Travel attendants, conductors and guides
  • *512 Cooks
  • *513 Waiters and bartenders
  • *514 Hairdressers, beauticians and related workers
  • *515 Building and housekeeping supervisors
  • *516 Other personal services workers
  • 52 Sales workers
  • *521 Street and market salespersons
  • *522 Shop salespersons
  • *523 Cashiers and ticket clerks
  • *524 Other sales workers
  • 53 Personal care workers
  • *531 Child care workers and teachers' aides
  • *532 Personal care workers in health services
  • 54 Protective services workers
  • *541 Protective services workers