Ethnic minority adolescents receive not only less formal mental health services than their ethnic majority peers but also less school-based mental health services. Little is known about the extent to which adolescents indicate their teachers help them with their mental health problems. The aim of the current study was to investigate ethnic differences in teacher-provided informal help for adolescents' internalizing problems, and whether these could be explained by differences in teacher-reported internalizing problems and teacher-adolescent relationship quality. A sample of adolescents at risk of internalizing problems and their teachers participated in the study (n = 229). Adolescents originated from four ethnic groups in the Netherlands: three ethnic minority groups (Surinamese Dutch, Turkish Dutch, Moroccan Dutch) and the ethnic majority (native Dutch). Results showed that only Moroccan Dutch adolescents reported considerably less informal help from their teachers for their internalizing problems than native Dutch adolescents, whereas Turkish Dutch and Surinamese Dutch adolescents were not found to differ from native Dutch adolescents. Teacher-student relationship quality and teacher-reported internalizing problems could not explain the differences in informal help between Moroccan Dutch and Dutch adolescents. Teachers reported significantly higher levels of conflict in their relationships with Moroccan Dutch than native Dutch adolescents, and for Moroccan Dutch adolescents, higher levels of conflict were associated with lower levels of informal help by the teacher.