Background: Knowledge about the living conditions among people with intellectual disabilities (ID) is globally scarce. Even in countries with good access to registers, this is often partly due to the absence of a single, comprehensive, nationwide register of individuals with ID or the inability to identify all individuals with ID within existing registers. In Sweden, the Halmstad University Register on Pupils with ID (HURPID) was established to fill this gap. HURPID is based on the population that left the Swedish Upper Secondary School for pupils with ID (USSID) in 2001–2020. Most young people with ID in Sweden are expected to attend USSID. The aims of this paper were to describe the construction, structure, and content of HURPID, to validate the register, and to provide examples of what it has been used for.

Methods: Based on school leaving certificates or corresponding, personal identity number, gender, educational programme, municipality where the school was located, and graduation year were registered. HURPID has been linked with various registers in projects addressing research questions about the target group's living conditions.

Results: HURPID consists of 26,910 individuals (11,078 women, 15,832 men), born in 1973–2003. Through linkages, knowledge has been gained about occupational patterns, psychiatric comorbidity, mortality, substance use, criminality and victimisation.

Conclusions: HURPID demonstrates the highest completeness of individuals with ID of working age in Sweden. This makes it possible to follow the development of adolescents with ID over time. As one of the most extensive and comprehensive registers of individuals with ID in the world, it also forms a unique register internationally. © 2025 The Author(s). JCPP Advances published by John Wiley & Sons Ltd on behalf of Association for Child and Adolescent Mental Health.