In Germany, every fourth child and adolescent suffers from a mental disorder during their time at school. Due to the significant amount of time that students and teachers spend together, teachers play an important role in protecting and maintaining students' mental health. Despite the importance of teachers for students' well-being, research on teachers' competencies in dealing with students' mental health problems (MHP), and their mental health literacy (T-MHL), remains scarce. We addressed this research gap by providing insights into teachers' experiences, cooperation, self-efficacy beliefs, and knowledge related to students' MHP. All 70 surveyed teachers stated that they had experienced various mental disorders. Most of the teachers felt supported by their colleagues and school principals when dealing with students with mental disorders. The majority also stated that they knew who to contact in school if they needed support, and more than one-third indicated that they did not know which external school support systems they could contact. Moreover, participants reported cooperating most frequently with school support staff and social workers, while cooperation with the youth welfare office and school psychologists was rare. Considering the different facets of T-MHL, teachers felt highly self-efficacious in perceiving physical, emotional, and behavioral changes in students and moderately self-efficacious in dealing with students. Moreover, teachers moderately rated their action-related knowledge of the MHP indicators. The results showed that recognizing the indications for MHP was not statistically related to dealing with them. This exploratory study contributes to empirical investigations of T-MHL. The findings are discussed in relation to teacher professionalization.