The aim was to analyse the performance of the pilot modules in a representative sample of the target population, to refine the scale structure, and to assess the retest-reliability as well as construct validity of the DISABKIDS modules. The sample was recruited from paediatric hospitals in order to have a homogenous setting. In order to ensure harmony between the DISABKIDS and KIDSCREEN questionnaires the field study instruments included the core items of both questionnaires, and coordinated core determinants, such as sociodemographic items and health status. The field study results provides the reference data reported elsewhere in the manual. Furthermore, core sociodemographic features of the DISABKIDS field study sample are presented. The DISABKIDS field study was conducted in an overall sample of 1606 cases, about equally distributed across the age groups 4-7 years, 8-12 years, and 13-16 years. Asthma was the only condition tested cross-nationally. In terms of severity of the condition, the sample was primarily in the mild and moderate range (50.7 % respectively 38.7 % of valid cases), however also included children with a more severe impact (10.6 % of valid cases) as indicated by clinical measures on severity assessment.