This report explores the extent to which different vulnerable groups in European labour markets are measured across 24 (27) data sets covering the European area. It studies the measurement of nine actor characteristics that have been associated with employment vulnerability: age, gender, sexual orientation, single parenthood, disability, religion, ethnicity, nationality and migration status. The inventory identified a number of measures that are relatively straightforward in regard to harmonisation. These include age groups and gender (binary), as well as migration status and nationality on higher levels of aggregation. A second set of vulnerable groups is identified indirectly, through questions on household composition and household grids. These are sexual orientation and single parenthood. Disability status has proven hard to harmonise, because the selected surveys operationalised the concept in different ways. There is relatively little data on respondents’ ethnicity, nationality, migration status and religion. These variables are often excluded from studies, or included only at very high levels of aggregation. Finally, the inventory revealed three data gaps. There are no surveys in the European data infrastructure that measure levels of citizenship rights or non-binary gender identity and the identification of sexual minorities respondents beyond co-habiting same-sex couples is impossible in most surveys.