Mental health and cultural and linguistic diversity in classrooms are part of students' lives. Both factors can lower the achievements of students and classrooms and pose a challenge for teachers. Yet, little is known about the effects on other areas of school life besides achievements. Also, the consequences for classmates and teachers as well as possible resources are mostly disregarded. Semi-structured interviews were held to investigate the diverse effects of mental health issues and cultural and linguistic diversity on students, classmates and teachers. In total 20 interviews were conducted, seven with teachers, seven with external professionals and six with students. Recordings were transcribed and analysed using qualitative text analysis. Results show that especially externalizing symptoms of mental health issues are a burden to classmates and teachers. Teachers face time management problems and emotional stress. Linguistic diversity constitutes a serious challenge at school for students, classmates and teachers. Yet, cultural and linguistic diversity also imports several resources like fostering openness and integration. Future research should expand this research to older children and investigate the specific needs of teachers.