The NEET concept has become standard vocabulary when addressing youth disengagement. Across countries, the definition is used to measure young adults at risk of social exclusion. Using sequence and clustering analyses on unique Danish register data, this article presents a longitudinal study of the temporal developments of NEET occurrences. This enables a critical assessment of the quality of the NEET concept as a proxy for measuring young adults at risk of social exclusion. The article demonstrates how four out of five young adults labelled NEET cannot be characterized as being at risk of social exclusion. Using quantitative analyses, the results confirm the criticism of the NEET concept in some of the qualitative literature and find that there is a need to discuss the applicability of the concept nationally to define who is at risk, as well as in cross-national comparisons of young adults not in employment, education or training.