The risk of late complications after a brain tumor in childhood is high. Both the tumor itself and the treatments give rise to sequelae that affect daily life activities. In this registry study, we explored post-compulsory education, i.e., further education following the nine compulsory years in school, in 452 cases born 1988–1996 and diagnosed with a brain tumor before their fifteenth birthday. They were compared with 2188 individual controls who were not treated for cancer. Significantly fewer teenagers and young adults treated for brain tumors in childhood attended high school or university compared with controls, especially individuals treated for embryonal tumors or optic pathway gliomas. A significantly larger proportion of subjects treated for embryonal tumors and craniopharyngiomas attended folk high schools, a type of post-compulsory school with a more accessible learning environment. For both cases and controls, we observed a positive correlation between parental education levels and attendance in high school and university. In our previous studies we have shown that children treated for brain tumors, as a group, tend to perform worse during their last year of compulsory school compared with their peers, and the current study confirms that these differences remain over time.