Previous research highlights that teachers’ beliefs, attitudes, and expectations regarding cultural diversity and immigration significantly influence students’ psychosocial and sociocultural adaptation. However, evidence from Spain on teachers’ acculturation expectations remains limited. This study analysed such expectations among 320 compulsory education teachers in Spain, examining the role of demographic and psychosocial variables. An online survey assessed support for cultural preservation, assimilation, and separation, alongside pro-diversity beliefs, intercultural sensitivity, and negative stereotypes. Results indicated stronger support for cultural preservation compared to assimilation or separation. Female teachers showed higher endorsement of cultural preservation, while male teachers supported assimilation more. Younger teachers more strongly rejected assimilation and separation than older counterparts. Cultural preservation correlated positively with intercultural sensitivity and pro-diversity beliefs, whereas assimilation and separation were linked to negative stereotypes and lower intercultural sensitivity. These findings underline the need to strengthen intercultural training, critical reflection, and inclusive pedagogical practices in teacher education.