This paper describes and discusses findings gained in a teacher training reform project at the University of Hamburg in Germany. In a newly implemented structure, pre-service teachers partake in an integrated model of courses that prepare them to deal with multilingualism in the subject classroom. For the first four semesters of the new model, a complex evaluation tool was employed in a pre-post design to better understand student competence development, curricular components of the teaching degree and student beliefs about multilingualism. This paper sheds light on the professional beliefs that pre-service teachers have about linguistic diversity and multilingual learners. The overall results show generally positive beliefs about multilingual learners, multilingualism in schools, and language support for multilingual learners. Moreover, the data show that multilingual pre-service teachers have more positive beliefs, female participants have more positive beliefs, and that there is a significant interdependence between beliefs and relevant opportunities to learn. Comparing the pre-test and the post-test data using explorative factor analysis, it can be shown that students’ beliefs are far more structured and follow a clear five-dimensional pattern in the post test, whereas the pre-test data can be described as diffuse and unstructured.