Occupation is a key variable in socio-economic research. In surveys, occupation is predominantly asked using an open response format, followed by field- or office-coding. Web-surveys can apply a closed response format, allowing for respondent’s self-identification when using a detailed list of distinct occupational titles and a search tree for navigating. This article summarizes the principles underlying the WISCO Database of Occupations for web-surveys, which includes a source list of 1,594 occupational titles in English, country-specific translations of these occupational titles, and a 3-tier search tree. The occupational titles are coded according to ILO’s international classification of occupations, ISCO-08. The database has been designed as part of the EU-FP6 EurOccupations project, measuring occupations with a greater precision than ISCO 4-digit by adding further digits, and is freely available from www.euroccupations.org. The WISCO Database is currently used in the WageIndicator web-survey on work and wages in approximately 50 countries, see "www.wageindicator.org":http://www.wageindicator.org.