In the revision of the Diagnostic and Statistical Manual (DSM-5), “Identity” is an essential diagnostic criterion for personality disorders (self-related personality functioning) in the alternative approach to the diagnosis of personality disorders in Section III of DSM-5. Integrating a broad range of established identity concepts, AIDA (Assessment of Identity Development in Adolescence) is a new questionnaire to assess pathology-related identity development in healthy and disturbed adolescents aged 12 to 18 years.