While in the school context, acculturation is often studied in relation to students of immigrant descent, the current study applies an acculturation framework to teachers mostly representing the mainstream culture. Specifically, we investigated whether teachers’ acculturation attitudes towards their students mediate effects of the perceived cultural diversity climate at school on teachers’ intercultural self-efficacy in culturally diverse classrooms. Analyses were based on reports of 186 teachers (14% of immigrant descent; Mage = 40.8; SDage = 11.8, 73% female) in 22 culturally diverse secondary schools in Southwest Germany. Path analyses indicated that perceived norms of cultural pluralism, and perceived norms of equality and inclusion are directly and positively associated with facets of intercultural self-efficacy. Moreover, teachers’ support for cultural maintenance amongst their students was associated with intercultural self- efficacy, but no mediation was found between climate and intercultural self-efficacy via acculturation attitudes. Implications for teacher training, educational practice and future research on the acculturation and adjustment of teachers in culturally diverse classrooms are discussed.