Chirine Cytera, Holger Muehlan, Marion Rapp, Audrey Guyard, Ute Thyen, Silke Schmidt, Henriette Markwart

• Background The Questionnaire of Young People's Participation (QYPP) was developed for use in children and adolescents. To track participation throughout transition from childhood to adulthood, we adapted it for young adults using focus groups. Aim of this study was to validate this measure, the QYPP–Young Adults (QYPP‐YA). Methods We recruited young adults with cerebral palsy (CP) and a representative, same‐aged sample of the general population (GP). The GP‐sample was split into two equivalent subsamples, one part to identify the factor structure via exploratory factor analysis and another part to test the resulting model via confirmatory factor analysis. Reliability and different forms of validity were investigated. Results The final QYPP‐YA includes 17 items assigned to six domains (Autonomy, Independency, Intimate Relationships, Interpersonal Relationships, Social Life, Online Communication). Scales show satisfying internal consistencies in the CP‐sample and in the GP‐sample, except for ‘Online Communication’. Convergent, divergent and known‐group validity were confirmed. Conclusions The QYPP‐YA instrument features promising psychometric characteristics to assess key domains of participation in healthy and disabled young adults. It provides a multidimensional, economic and sound assessment for use in population surveys and clinical trials.