This study examined the categories that states use to classify and govern migrants. Unaccompanied minors and adult asylum seekers are treated very differently regarding their asylum cases and residence permits. The study focused on Germany, where the courts and youth welfare offices commission age assessments to decide whether young migrants will be considered minors or adults. These assessments are carried out by forensic medical examiners and social workers, respectively, who work with very different understandings of what constitutes age.